Although Cowboy Bebop takes place in a setting where mankind has developed hyperspace gates and terraforming technology, many of the cities built on other planets (especially Mars) feature architecture that would not be out of place in the late 20th century on Earth. Automobiles look pretty much the same as they do now; most of the weapons seen on the show are actually real-world firearms; electronics are dated, by modern standards.
The comic book Good as Lily from DC's short-lived Minx imprint is very guilty of this. An 18-year-old girl meets herself at age 80, and she acts, talks and dresses just like an 80-year-old woman of today even though she comes from 62 years in the future.
There were many advances in technology between KOTOR and the film trilogies. Bacta tanks (more of a discovery than research but still), capital ships were able to hold many more weapons batteries (You know those Sith Destroyers which were the pinnacle of shipbuilding in their day? They were armed with 20 laser cannons and 4 turbolasers. Republic Hammerheads had 3 turbolasers. The late Republic and Imperial-era ships could hold hundreds and dozens, respectively. Furthermore, the Empire didn't greatly advance technology in any beneficial way. It spent most of its science budget on superweapons and torture devices that were only useful for keeping the terrified and discontent population in check. Nothing greatly beneficial to civilians' quality of life was ever made. The Empire also virtually halted the exploration of new territories, which had been a major source of innovation to the Republic because new alien civilizations to trade with often meant new technology. The only interest Palpatine ever showed in alien science was Sii-Ruuvi entechment and we all know that one turned out.
Not to mention that between KOTOR and the prequels were the highly destructive New Sith Wars, a thousand-year period of more or less constant galaxy wide conflict and decline that regressed technology and infrastructure by a significant degree. By the end of the period, the Republic and the Jedi were so devastated that even though they decisively ended the (apparent) Sith threat, the only way to prevent the Republic's utter collapse was to institute a massive decentralization that marked the fundamental end of the republic as it had been for 24,000 years before. So there's more than enough in the EU to justify relatively similarly levels of technology in the two eras, much like how (in Europe) The Late Middle Ages and The Renaissance are roughly equivalent to Ancient Rome despite occurring over a thousand years later.
Such wars are probably the only conceivable reason such a thing as "lost knowledge" and "forgotten technology" exists at all in a futuristic society with sector-spanning data networks and implied multiple redundancies. Likewise, the loss of knowledge about events during the Old Republic period in the presence of computer systems and droids operational over many thousands of years may be a result of massive databank Retcon by various conspirators who would really like to bury the secrets of the past. An example would be hiding the location of Kamino in Episode II.
The real reason is most probably because the Tales of the Jedi comics have visual designs that look almost nothing like what many Star Wars fans are familiar with. With the Mandalorian/Jedi Civil War taking place less then thirty years after the last Tot J comic, it's likely BioWare changed it largely so that fans who hadn't read the comic wouldn't complain that the games look nothing like Star Wars. Many of the Darth Bane novels (which take place DURING said Dark Age) seem to show the tech being pretty much what we see in episode I for instance, with nothing changed except the presence of the Sith, with even many of the ship descriptions in the novel seeming similar to what was seen in the KOTOR games, like the Hammerhead and Sith Destroyers. The description of loss of reliable interstellar communication is actually something that happened during the Empire too: only the Empire had long-range communication that was instant, so if you weren't part of the Imperial military you didn't have reliable info on what was happening off-world.
The Empire halted exploration of the Unknown Regions because of the Yuuzhan Vong threat, which the Emperor knew was going to arrive soon. Thrawn's naval garrison in the Unknown Regions was the only thing keeping the Vong at bay, and when he and his fleet returned after the Emperor's death in order to command the Imperial Remnant, the galaxy's last bulwark was gone.
In Time takes place at an unknown point in the future (they avoid mentioning any years), when genetic engineering has allowed all humans to stop aging at 25. In order to avoid overpopulation, all people must, essentially, work to stay alive. Time literally becomes money. The rich can live forever, while the poor live day-to-day. Those who "time out" suffer a heart attack and collapse dead. Certain wealthy characters are mentioned as being at least a hundred years old. This means that this is, at least, the 22nd century. However, nothing much changes in terms of technology, besides genetic engineering. Guns, cars, and buildings still look the same. The poor still use pay phones. Not a single flying vehicle is shown, though, even regular old airplanes.
It is justified, since the immortal wealthy don't really need new technology. If one can live forever, why the rush to make anything new?
Actually, during the beginning monologue, Will narrates that the timeline is 2169, which, given the dypotian setting, is not a large leap from today.
The "Kim tells her story" frame in Edward Scissorhands. If the main plot is set in a stylised version of the mid 1960s, and Kim is 18ish, she was born in the late 1940s: therefore the frame, in which Kim is elderly, must take place well into the 21st century, probably in the 2020s or so - certainly long after the film was made in 1990. Yet, if anything, it looks rather old-fashioned even for 1990; it's not really differentiated at all from the main Sixties setting.
While Judge Dredd was set in a futuristic universe with sprawling skyscrapers and impractically-designed buildings, the 2012 reboot Dredd could easily pass for the modern world. Aside from the Lawgivers, all the tech featured isn't something that couldn't have been made today, including a UAV doing a flyover in the beginning. Neill Blomkamp's films helped inspire the film, and it definitely shows in the presentation.
Slightly averted in the Novelization of Star Trek: The Motion Picture written by Gene Roddenberry (or at least with his name as author) talks about how a lot of the people on Earth are “New Humans” who have evolved to be more peaceful, less driven, and mentally calmer. Then you have people like Kirk who still use family names, still are willing to use violence, still have inner demons to drive them on…
Subtly referenced in the 2009 reboot, with Pike's description of Kirk possessing an adventurous spirit that Star Fleet has mostly lost ("act first, ask questions later").
The Gbaba, hostile aliens in the Safehold universe, are suspected by the human race (whom they are busy wiping out) to be stuck in this; evidence suggests the Gbaba have seen few, if any, significant advances in technology for centuries or more; one example given are the warships; one captured warship was built at least two thousand years earlier. It is otherwise identical—software, computers, weapons, sensors—to a recently constructed warship.
In Vladimir Vasilyev's Big Kiev Technician, it is the year 368,764, but everything looks like it has at the end of the 20th century, except that many cities are now Mega Cities. The world is, inexplicably, also populated by fantasy races like elves and dwarves, although the short-lived humans are still the majority. Nothing has changed in at least 10,000 years (according to records), and most people forgot how things work. Technicians and scientists are the societal elite, as they know the "formulas" for taming and operating machines. Machines themselves are also somehow alive, or at least perceived that way. Nothing in the book explains how things got to this point. The ending of the book signals the End Of An Era of stagnation where most of the "tamed" machines shut down in the presence of manufactured ones, starting the age of rediscovery and progress.
The short story collection Big Kiev Witcher includes more high-tech things like Spider Bots and deadly security fields that won't harm children or witchers.
Earth in the Old Man's War series by John Scalzi. There still seems to be TV, Time Magazine, Newsweek, etc.. The Colonial Union keeps all the very high tech to itself and reminds Earth of this via an orbital elevator that should not exist via the physics they know.
Kenneth Bulmer's The Secret of ZI takes place nearly 300 years after the Earth was conquered by Human Aliens, but everything seems exactly like the date it was written. Partly justified by the aliens having prohibited all techological advance in order to keep their superiority, but this doesn't account for the total lack of cultural change, even on the most superficial level of slang and fashions. Of course this is because the plot (a resistance movement preparing for an interstellar counter-attack at sublight speeds) requires a delay of centuries, but the author didn't want the distractions of inventing a future world.
Played with and justified in the Tomorrow War trilogy by Alexander Zorich, which takes place in the 27th century, when humanity has already colonized several planetary systems. While the culture and society on Earth are suspiciously similar to our present, a mysterious phenomenon known as "retrospective evolution" causes human colonists in remote planetary systems to revert to cultural norms of ancient societies. Two such societies are shown - Concordians, who are emulating Zoroastrian Persians, and Great Muromians, who are emulating pagan East Slavs. In the third book it is revealed that the earthlings were also affected by that phenomenon and were reverted to... the late 20th century.
In the early parts of Isaac Asimov's Foundation trilogy, the Foundation's enemies are somewhere between here and Medieval Stasis, having lost the knowledge of most high technology. Specifically, the lack nuclear power, one of the hallmarks of the Modern Age. The use of their technological edge (veiled in mysticism) is what turns the resource-poor Foundation into a regional superpower.
The narrator of How I Met Your Mother never mentions anything dramatically different about the future and portrays it as exactly like the present when he mentions it at all. But then, a father telling his children a bedtime story would not need to remind them about the Zombie Apocalypse that happened last year. (One minor exception: He mentions that in the late '00s, people used to go to these things called "gyms.")
Though Ted being Ted, it's likely that he's simply pointing out the lethargy of "today's youth".
In a recent episode, Ted was at an airport in 2021 where he comments that they live in a time where cell phones can project holograms, but flights are still cancelled due to drizzle.
Mostly true about the Distant Finale of Mad About You, though it is implied that the lowest-common-denominator of pop culture has dropped and the world is on its way to becoming a crapsack.
In Dark Shadows, when Barnabas and Julia travel to 1995, there are no noticeable changes in costume or technology.
Battlestar Galactica suffered from this, and the flashbacks to the pre-genocide Colonies got worse and worse as the series went on.
Somewhat justified on the ships. BSG itself was a 50 year old military vessel. They deliberately point out that they use old, unnetworked computers because the technology was too vulnerable to Cylon attacks, and robotics was obviously abandoned after the wars. The bare-bones existence on a battleship wouldn't be likely to have many other obvious technologies. Their medical technology doesn't seem any more advanced than ours, but this is 150,000 years ago, and not all technology develops at the same rate.
Strangely, its short-lived prequel series Caprica seemed as advanced as the later Colonies were (with technologies we never saw in the original BSG series), but had a completely different visual aesthetic, looking something like a futuristic version of the 1930's/40's. It seems to be implied that after the First Cylon War (which takes place after Caprica), the Colonial government outlawed many of the more advanced-looking technologies we see on the series, such as computer networks.
In Stargate Universe, it is revealed that, due to a Timey Wimey Ball, duplicates of the Destiny crew ended up on a habitable world 2000 years ago and were forced to establish a colony. While they had to do everything from scratch, lacking the necessary tools to construct anything beyond rudimentary housing at first, multiple Time Skips show that the Novus colonists advanced pretty fast and had a decent-sized town (with modern architecture) within 3 generations. Time Skip again to modern day. The Novus society has grown and expanded, but does not look much more advanced than modern-day Earth. Yes, the colonists had to struggle to start, but they had a huge head start with technology and science (admittedly, they do manage to cure several diseases that we still can't), so they should have advanced much further than what we see.
They also manage to build large colony ships capable of housing thousands of people for a century of more...with no FTL. Compared to other canonical civilizations like the Tollans who progressed way further (to the point of building their own "Stargates") in roughly the same time the Novus people are downright dragging their feet.
Sometimes, but by no means all the time, happens in Doctor Who. Humans will be wearing typical clothes of today, talking in typical accents of today and using traditional vehicles and guns, even as far into the future as year 100 Trillion - although it is stated humans have evolved into beings of gas and back and more in this time. Maybe they just happened to be at exactly our level of technology again by that time.
Another example is an episode where Great Britain owns a city sized starship in the distant future, propelled by a space whale, and yet features fairly normal early 21st century looking rooms in at least some areas of the ship.
On the other hand, episodes set in the future do usually have some futuristic element like energy weapons (that resemble modern guns) and advanced tech...though the humans also tend to wear more or less modern clothes.
In The Sims 2, you can play through multiple generations of families, but the world never changes at all. Granted, Sims only live about 70-80 days, so ten generations of Sims takes about one real-world year.
SimCity games (except 2000) run the trope. Your city could be in the year 2300, and yet architecture, fashions, trends, and industry are pretty much the same (yes, even the high-tech industry doesn't get any higher or more improved). SimCity 2000 introduces some futuristic power stations and the giant "arcology" apartment buildings, but their presence doesn't seem to have any effect on the rest of the city.
Of course, thanks to customizable tilesets, you can change the architecture from 1950, to 2050 and beyond. This is purely cosmetic though.
The Halo series is a rather peculiar example of this. Much of the space (yes, they use FTL drives) and computer technology (human-like AI) seems to fit it's time frame- the mid 2500's- but the rest seems to be stuck in the mid 21st century at best. While domestic technology isn't explored that much, it's roughly something that'd be expected in the mid 21st century. Cars and trucks and the like are about the same as modern counterparts, only more streamlined and perhaps some other unseen differences. Cities are abit more advanced, but only really seem to be more streamlined and digitally integrated, with flashy roadways and city-wide AI's.
Military weaponry shows the most extreme case of this. Many of the firearms are virtually identical to modern day counterparts, with the only visible differences being things like digital readouts on ammo. Soldiers use some relatively advanced headgear and armor, but nothing approaching those of the Spartans. Ground vehicles are also similar, with some, like early variants of the scorpion tank, resembling something from the 20th century. Because of all this, humans are amazed at the covenant's use of plasma weaponry and shields.
However, it could be for most of those examples, of using technology that works, and is strong and robust. It's a case of Boring, but Practical vs. Cool, but Inefficient; ground vehicles use tires and treads because, hey, they're simple and work. Guns have solid little micro-comps built in that'll keep working under just about any conditions. As for a simple reason behind this: the human race has been at war for its life for a generation. Efficient use of tech intended for large scale deployment saves alot on that level.
Even some of the aerial vehicles aren't safe from this. In Halo: Reach, there are helicopters that still use regular blades.
The "primitive" human weapons are pretty much always better than the "advanced" covenant stuff though, on the ground anyway.
Compare to the Covenant's advanced technology that they got by looting the Lost Technology of the Forerunners. It is implied that the Covenant only has a limited knowledge of how the technology works, and thus makes very inefficient use of it, compared to the humans making the most of their relatively primitive (but effective) technology. Or, for that matter, making improvements on tech they stole from the Covenant from time to time.
Medical technology however has made a lot of improvements, such as cancer being almost unheard of (as easy to remove).
Perfect Dark, in 2023, is appreciably futuristic, with flying cars and motorbikes, cloaking devices, guns disguised as laptops, laser weapons, teleporters, etc. (save for some of the guns and the computers), but its prequel, which is set a mere 3 years earlier, still has contemporary-style vehicles and architecture, and the nightclubs apparently still use vinyl records, as evident by the Record Needle Scratch when the music stops.
San Francisco Rush 2049 has futuristic buildings and a few futuristic cars, but most of the cars are straight out of the 20th century. Not to mention contemporary gas stations, subway trains, cable cars, windmills, boats, etc.
To be fair, the cable cars haven't change much in 120 years, why would they now? Subway trains as well.
In the Command & Conquer: Tiberium universe, whenever civilians appear in FMV cutscenes, they look straight out from whenever the game was made. Especially egregious in Tiberian Twilight which takes place in 2071 but a shot of a street in the final cutscene looks like modern-day Los Angeles.
Largely averted in-game though, where GDI cities and settlements have a more Twenty Minutes into the Future flavour while the cities that look present-day are crumbling Yellow Zone hellholes whose governments collapsed decades ago.
One level of Descent 3 takes place in Seoul, Korea, which seems to be mostly stuck in the 20th/21st century.
The industrial revolution in the world of Arc The Lad happened 1000 years prior to the first episode, yet appart from a few gadgets used by the Romalian military, technology never went beyond the level of the late twentieth century.
The Mass Effect universe operates on a variant of this. Since every advanced civilisation gets culled every 50,000 years by the Reapers and the technology left behind influences the development of inhabitants of the next Cycle, the galaxy can be considered to have remained technologically stagnant for millions of years.
In Dan and Mab's Furry Adventures , the world is kind of an odd mesh of modern and medieval trappings, suitable for a fantasy world. Fair enough, but in Abel's story, which begins four hundred years before the main plot... everything, everything, is exactly the same. There is not a single visible difference to the scenery - other than Jyrras's inventions, things that are modern in the main strip are modern, and things that are pre-modern are pre-modern, with identical architecture and fashions.
Explained to some extent by the existence of the magical, long-lived Creature races. When you're 7000 years old, a mere four centuries isn't that long. Furthermore, many Creatures are said to dislike technology. Some view it as the recourse of feeble Beings who are too weak to survive without it, while others regard it as a threat to their power and slap anyone who gets too clever down. Jyrras is shown to be keeping a lot of new technology under wraps specifically to avoid this kind of attention.
Lampshaded in the Stroker and Hoop Christmas special. Stroker and Hoop travel forward in time to meet a future version of Coroner Rick, and though he knows the names of some new things that are happening in the world, he doesn't understand any of them because he's an old coot.
Parodied in Family Guy Presents Stewie Griffin The Untold Story where the only real advancements in thirty years are time travel. Televisions, cars, and DVD players haven't advanced much at all.
Accidental example in the Captain Scarlet reboot, which is otherwise pretty good at maintaining a Twenty Minutes into the Future look and feel; during the Car Chase scenes, any vehicle that isn't relevant to the plot will look very similar to a late 20th or early 21st century design. This is probably because they're a stock 3d model being used because there wasn't the time or budget to do anything more elaborate for a vehicle that'd only be on screen for a couple of seconds.
The so-called Dark Ages revered ancient Rome because its architectural achievements were only equaled during the time of the High Middle Ages. The Renaissance was partly an attempt to revive classical traditions over the medieval art forms.
Although amusingly enough, the so-called Gothic architecture developed during the Middle Ages was technologically more advanced than anything done in the ancient Rome, but the Renaissance people thought it was crude and barbaric because it diverted from the Roman aesthetics.
Historically Truth in Television. While technological progress has occurred throughout history, during much of history new technologies were unlikely to be widely adapted within a short period of time due to logistical issues, meaning that 20 years on, the world tended to look fairly similar, barring a major war. As time went on, the time lapse between something being invented and it becoming common dropped immensely, with the industrial revolution greatly decreasing the time gap between invention and widespread use. The 20th century may have been the apex of this, with extreme, world-altering advancements happening on a decade by decade basis, and rapid changes in aesthetics occurring particularly in the second half of the century as technology allowed slimmer, more efficient forms to exist. Interestingly, this trope may return to reality within the next century or so; most modes of transportation have changed little in decades, and as computers reach new heights, their extra power is becoming less and less necessary to the masses, reducing the replacement rate.
Conspiracy Theorists claim that oil companies, technology companies, and other large industries intentionally keep the world in this state, despite obvious real life aversions. Very often much of this is based on a lack of understanding of the costs of new technologies (such as the issues with solar power - in some cases it may cost less in the long run, but the costs are almost all up front, meaning that you're paying for 20 years of power today, an unpalatable proposition), or the impossibility of some devices (an internal combustion motor using water as a fuel, for instance, is only possible if the water is being reacted with highly toxic chemicals like fluorine, and as such is not useful, let alone perpetual motion machines and similar devices).