The entire town in The Boxtrolls really but a special mention should go to Lord Portley-Rind; if it's not about cheese, he has absolutely no interest.
Played straight and averted in The Christmas Tree. Judy's a decent person, if a bit dim, and genuinely cares for the children. The mayor, however, doesn't seem to have the slightest inkling that anything is amiss at the Orphanage of Fear, and is perfectly willing to fork over large sums of cash to Mrs. Mavilda without much question.
Downplayed in Coraline. Coraline's parents didn't do much and aren't especially nice, but they had pretty good reasons not to believe Coraline's Cassandra Truth. On the other hand, Bobinsky gave Coraline a subtle warning and Spink and Forcible also warned her that she was in terrible danger. And at the end, Spink and Forcible gave Coraline an important item to help her find the eyes of the ghost children.
Justice League vs. Teen Titans: Zig-zagged — Batman can't keep Damian on a leash forever and thus opts to send him to the Titans to cool him off. However, when the potential for Raven's danger is made real, the League steps in, not wanting a threat like this to spread. That last bit is vastly different from both the comics and previous animated variations, which they are either ignored or Adapted Out.
The Land Before Time III. Not long after a meteor storm, the Great Valley's main water supply, a river running down from beyond the wall, mysteriously dries up. Rather than say, investigating the river's source (they could have sent fliers if they were worried about carnivores), the adults decide to wait in the valley and hope the water returns. In the meantime, water is running low, tempers are running high and all the food is quickly dying off. In the end, it's the children who accidentally find out that the water was blocked off and the adults can't agree on a plan of action and eventually, the children save the day by accident.
This is a very common occurrence throughout the series. None of the adults want to risk personal safety going out into the Mysterious Beyond for any reason whatsoever, leaving the children to do everything themselves.
In the 4th film, where Littlefoot's grandmother (who had been willing before to leave and search for a flower with healing properties) and the mother of a new character not only fail to go after their runaway children but don't even seem worried or concerned that the kids are gone.
My Little Pony: Equestria Girls has Principal Celestia and Vice-Principal Luna as reasonable authority figures... except that most situations fall far outside their areas of expertise, due to most problems the main characters face being magical in nature. Leading to moments like them getting brainwashed along with the rest of the student body in Rainbow Rocks. They can also be oblivious, such as the first Equestria Girls having them unaware of Sunset's bullying and control of the school, or being easily fooled by falsified evidence in a scene pretty much designed to give credibility to the Satellite Love Interest.
Friendship Games technically has this in Principal Cinch of Crystal Prep. She isn't useless in terms of the film's actual plot, but it regards to her actual job as a principal, she's pretty bad. She says point blank in her Villain Song she has always known that human Twilight Sparkle has always been an outcast at Crystal Prep, but has done nothing to help her. In addition, she blackmails and pressures her students to do well in the games for her own reputation and isn't above spying and cheating. Dean Cadance is a lesser example, she is a reasonable authority figure just like Celestia and Luna and it is obvious she cares about Twilight, but isn't seen helping her against peer pressure and bullying on screen. Instead she just offers her good advice knowing where she will be happiest.
With Doof, this is to be expected, despite his insistence to the contrary. However, he zig zags this trope as he sometimes is useful to the plot, but is also often enough an obstruction. He already built a compatible spaceship for the kids to fly to Feebla-Oot, but he's just about useless when it comes to flying it, and it actually doesn't come with an ion shield, despite the planet that they'll going to being blocked by an ion field. Once on the planet, he tries to lead the group to the fortress that they believe Candace is being held, but gets them all hopelessly lost in the jungle, although he does stumble upon the fortress eventually. He also uses one of his inators to transport himself, Vanessa and Perry back to Earth, but his first attempts have failed due to there already being a chicken on the planet and it was Vanessa that remembered that he had another setting to have them switch places with the furthest chicken. His inator was also responsible for sending the Big Doctor and Mama back to Feebla-Oot to save the day, but it was Candace that ended up using it for this purpose.
Played straight with every other adult on the planet Earth. Absolutely no adult was involved in fighting off the alien invasion, except for Doof who shows up about halfway through. When the aliens first show up, all the adults present were too distracted by the destruction of their statue to even notice. When they do notice, the aliens immediately release their mind controlling spores on them, brainwashing them. Only the kids had masks to protect them from the spores and thus were able to participate in the fight, even Doof himself was able to get one to prevent himself from being brainwashed by the spores.
Zigzagged in A Cinderella Story. While the school staff are clearly horrified by the humiliation Sam receives at the pep-rally, none of them punish Shelby or the other students for their bullying. That being said, they're clearly on Sam's side when she hooks up with Austin, who left Shelby.
In Aliens in the Attic, the aliens' Mind-Control Device is ineffective on kids. Naturally, it's up to the kids to save the day. However, a mind-controlled grandma becomes very useful when the kids steal the controller.
Bad Moms: Applies to the protagonist Amy's children Jane and Dylan. Amy quits her motherly duties to party and run rampant. She doesn't appear too concerned about her children missing meals or falling behind in school, and insults them at every chance she gets whenever they ask her for help. She then snaps right back to her senses when the kids run away to their dad and desert her as payback for her neglectful behavior.
Battle Royale. Not only does the government allow the capture of entire classrooms of children, but they allow putting them on an island, giving them deadly weapons, and telling them to go kill each other, last one alive wins and is free to go. On top of that, the parents never even TRY to save their children from being murdered, and instead the entire country (or possibly even the world) allows it to happen, waiting for the competition to end and see the winner. The protagonist, Shuya Nanahara, loses his father who commits suicide by hanging himself with a belt without any concern that Shuya now has to fend for himself, and Mitsuko's mother tried to pimp out Mitsuko when she was only 6 years old to a pedophile for the money.
In the original novel, most parents, upon hearing their children have become part of the Program, merely resign themselves. Those who do resist are gunned down.
This is true in both the manga and novel; the first chapter of the book hints it, and the manga integrates it into at least one character's back story.
Played straight when the kids in Bradley's Summer stop a terrorist plot, and then decide to chase the terrorists after they'd become kidnappers, the adults are all like "Good luck!" and do nothing to try to help the kids or let the cops handle it. Subverted later on however, when one of the adults actually does do something useful: knock out one of the terrorists while he's holding a gun to the kids.
Subverted in the Bring It On film series. Most of the featured cheerleading squads are depicted as being autonomous, but they're also comprised of high schoolers who are either nearly or legally adults by the time everything is said and done.
In The Candy Snatchers, every adult who isn't evil is this. Sean's parents unknowingly foil all his efforts to rescue Candy, while Candy's mother is a drunk who never questions why she hasn't seen her daughter in days.
Most of the adults in A Christmas Star either ignore Noelle's warnings about the Corrupt Corporate Executive trying to destroy their village or angrily rebuke her for trying to stop their town's main form of income being closed down or everyone in the village being made homeless! Although when the villain's boss finds out what his employee has been doing (mainly, trying to demolish the village to create an amusement park instead of developing in the local area) he fires the man instantly.
None of the parents of the girls in the film play a significant role. Amy's mother is the one who appears for the longest time.
The staff at their school are mostly ignorant if not outright passive with what the girls do and they only ever intervene if a full-on fight breaks out.
The Good Son has Elijah Wood's character trying to tell the adults what a monster his cousin is, but nobody believes him.
The Fratellis in The Goonies suffer this from time to time in their confrontations with the Goonies. They seem to be able to handle the cops (and Feds) just fine, but they can't quite handle a bunch of teenagers.
The three children in Hocus Pocus try to inform adults and enlist their help against the witches. It always fails. It doesn't help that the witches turn around Max's attempted warnings to their advantage (they pretend that he's giving them an introduction and give a musical act note "Oh no, she's singing from a distance!") or the fact that they enchant a large number of adults to "dance until [they] die". Then there's the fact that the the witches have come back from the grave prank has probably been played a million times in that town given the local notoriety of the events surrounding said witches.
Home Alone: Not only was Kevin's family careless enough to abandon him twice when they go on Christmas vacation, but not a single adult or authority figure notices anything suspicious about a child shopping or regularly going out by himself. Heck, Kevin even manages to check into the Plaza Hotel alone in the sequel by fooling the hotel staff with his Blatant Lies, which Kevin's mother even calls them out on. Even the police are like children since they are never able to catch Harry and Marv, and when Kevin's mother sent an officer to check on her son, he just knocked on the door for a while and then decided that there's nobody home. The only competent adults are Old Man Marley and the pigeon lady whom Kevin befriended and Mr. Duncan, who even donates the money from his toy store to save the ill children in the hospital on Christmas.
Joshua's only use for adults is to be pawns in his plan.
This was subverted in The Karate Kid (2010). Mr Han trained Dre for the tournament. Dre's mother supported him and would have beat the snot out of the kids who messed with her son, if she knew who they were. And the school principal sent both Dre and Cheng out after Cheng purposely tripped Dre, not favoring one side over the other. And she kept an eye out for Dre on the school trip, indirectly preventing Cheng from bullying him.
Jurassic Park III: Eric is stranded alone for eight weeks on an island said to be the single most dangerous place on Earth, and not only manages to not get eaten by a dinosaur, but manages to eek out a decent existence; he has a secure shelter inside an overturned water truck, and fends off the dinosaurs with only a cache of gas grenades, a homemade ghillie suit and the dino knowledge only a twelve year old could possess. By contrast the adults of the film, especially Eric's parents, have a vice grip on the Idiot Ball and have (near-)fatal run-ins with a Spinosaurus, a Rex and a pack of raptors all in the space of a single afternoon.
Just One of the Guys, being a teen comedy, plays this straight. The main characters' parents leave town for two weeks and two high schools are depicted as essentially devoid of responsible adult figures.
The Karate Kid (1984) plays it straight and subverts it. On one hand, Mr. Miyagi is there to stop the fighting between Daniel and Johnny. On the other hand, the kids' parents do nothing at all to prevent the fights. Daniel's mom provides moral support for her son, but doesn't do much. Ali's parents shrug off the fighting like it is nothing. Johnny's parents don't even appear in the film.
Kick-Ass. Dave alias Kick-Ass is a 17-year-old boy, and as a superhero far from being Badass Normal. He is known to have fought against three gangsters to protect an innocent. But later the mafioso of New York believes that he is the one who kills his subordinates and hurts his "company". Still, neither the people who work for him, nor the New York police, who are partially corrupt, can track him.
Red-Mist, another teenager who is a supervillain, can find Kick-Ass, however, within a day and lure him into the trap because he is a superhero. A simple teenager had more success than mafia and police together.
The film also features Hit-Girl, who is an effective, badass Action Girl.
It is inverted by the superhero Big-Daddy, who is by far the strongest fighter in the movie. But even though he is one of the few, competent adults, he is far from being morally pure. At best, he is an anti-hero.
Part of the charm of The Little Rascals film series was that the kids would regularly (and unintentionally) teach the adults a lesson.
Let Me In one of the main themes of the film is how none of the adults in Owens life protected or helped him in anyway. Despite the fact he was deeply lonely, and openly being tortured by bullies and coming back to his apartment with bloody cuts. Its even reflected in the cinematography of the film where the director chose to never show his parents on screen, his mothers face obscured throughout the entire film and only his fathers voice making an appearance.
The Lost Boys has a group of 12-year-old vampire hunters attempting (and at one point succeeding) to kill the group of teenage vampires. In fact all the main characters are younger than 20 with the adults being unaware until the big reveal at the end where one character displays he knew what was going on all along. Even then, he doesn't know everything that was going on, although he immediately knows that his house has just been destroyed in a vampire attack. That his daughter was dating a master vampire appears to have been completely unknown to him.
In Mikey the only characters that seem to display any common sense about Mikey's behavior are his teacher and Jessie.
Minutemen: One of the reasons Virgil comes up with the idea of helping the other kids like them at the school is because the faculty there doesn't seem to be doing anything about it. At one point, they find Vice Principal Tolkan in front of a vending machine that Chester is currently stuck inside, and doesn't seem to bother doing anything about it on account of not being able to "change the way high school works.
Similarly, instead of helping a bare naked Chester get his clothes back from bullies, Tolkan tells him straight to his face that helping him would mean that hed be "breaking the food chain".
Mystery Team. The main characters insist that they're more suited to solve the case than THE POLICE.
The Night of the Hunter: Rachel Cooper, the foster mother who takes in the Harper children, is the only adult in the film who is immune to Harry Powell's charms. Uncle Birdie does put in an effort, but after he discovers the mother's body he apparently doesn't report it because as the town eccentric/drunk he fears people will blame him.
This is justified in Nobody Knows. The adults can't help because they don't know the situation and the kids don't tell them either. Not helping is that Keiko (the kids' mom) rented the apartment without telling the landlord about her two youngest kids, so telling the landlord could get them evicted
In the Hallmark Channel made-for-TV movie The Santa Incident, Santa has to rely on the help of a couple of kids. Most of the other adults are Homeland Security goons who mistake him for a terrorist.
In SHAZAM! (2019), none of the staff stop the Breyer Brothers' bullying nor even punish them beating a kid with a crutch should've got them expelled, let alone hitting him hard enough with their truck to leave a scratch on the paint, right in front of the school in front of dozens of witnesses.
Sky High has the Commander and Jetstream as the only competent heroes shown in work, but they are taken down in seconds by the villain in the finale. Principal Powers appears to be competent but she is only seen putting students in detention. Anything worthwhile is done by adolescents. Even the villains are all young. Sort of. (Except Stitches, but he's basically controlled by Royal Pain anyway.)
The Social Network. Granted the main characters aren't small children, but all the adults they go to for help simply blow them off — Prince Albert, the lawyers (one can almost forgive Mark for his Jerkass behaviours towards them) and most of all the Harvard president Larry Summers.
Terminator 2: Judgment Day: John Connor's foster parents Todd and Janelle are very neglectful of him, which angrily coerces John to spend his whole time outside home. Later on, T-1000 mimicking Janelle on the phone calling John "honey" and offering him beef stew for dinner makes John point out Janelle would never do something like that.
This was probably the single worst thing about the 2004 Thunderbirds movie, which shoved most of International Rescue out of the way to leave the plot to the Kid-Appeal Character Alan Tracy, Brains' son, and Tin Tin (all of whom are pre-teens). Yeeah.
The main character in The Tin Drum realizes this and refuses to age past 3 years old. This means that he eventually becomes a chronological adult but remains a Spoiled Brat of a child.
In the first Transformers movie, much of the first tier of authority that Sam Witwicky encounters regarding the title being is best summed up by his disbelieving question of a police officer, "Are you on drugs?!" This only applies to the civilian adults. Those involved in the military usually perform rather well considering the circumstances, even if it's not always the best actions to take.
Trapped: The Alex Cooper Story: Most adults, from Alex's parents to the police, turn a blind eye when Alex, a teenage lesbian, tries to escape from the Simms and their brutal conversion therapy camp. They all know what the Simms do and how they're doing it; they simply don't care, agree with this or can't be bothered.
In WarGames, two teenagers are the only people who seem to be willing and able to avert nuclear holocaust, while parents, four-star generals and nuclear scientists act befuddled or indifferent.
In The Way, Way Back, lonely teenager Duncan is ignored by his mother, Pam, who seems only concerned about pleasing Trent, her overbearing boyfriend. Pam doesn't notice Trent saying horrible things to her son until the end of the movie. Trent, Pam and their neighbor also smoke pot and ignore their teens when they get stoned. Averted with Owen, the water park employee who notices Duncan is unhappy and lonely and becomes a friend to him.
In What We Did on Our Holiday the children end up honouring their granddad's wishes and giving him a Viking funeral after he dies on the beach because the adults are too busy getting ready for a party and arguing for them to be able to tell them what has happened.
Miss Gulch in The Wizard of Oz practically controls half the county even forcing Aunt Em and Uncle Henry to surrender Toto. In the Land of Oz Dorothy looks to many adult figures to solve her problems such as Glinda and the wizard, but the wizard is powerless. However Dorothy discovers the power to return home was inside of her and didn't need help from either Glinda or the wizard.
In Massacre at Central High, no adults even appear until the final scene. David won't tell anyone about the extreme bullying at Central High because "tattling's not in my nature," while Mark knows David is a Serial Killer but doesn't tell anyone out of personal loyalty. Gets to ridiculous extremes after three kids are killed by explosions on campus on the same day, and there's no investigation at all.