Alice used to be so poor that she couldn't afford shoes... But even as her financial situation improves, she has grown so accustomed to the lack of shoes, that she feels perfectly confortable without them.
Alice is a Hikikomori and doesn't feel fine with shoes and/or socks on, even if someone finally gets her outside.
Alice suffers from foot injury caused by wearing shoes, such as plantar fasciitis, and going barefoot eases this.
Alice has an extreme fear of getting a fungal infection such as athlete's food and/or having smelly feet, so avoids shoes to deny the optimal conditions for their development.
Nobody in Alice's friends and family, country, or species wears shoes.
Alice lives somewhere with an environmental condition that makes shoes impractical/dangerous to wear, or too difficult to obtain.
Alice lives on a tropical island where shoes aren't really needed anyway.
Alice never goes or is seen anywhere without shoes, even while swimming or practicing any activity where being barefoot would be expected / required.
Alice always goes barefoot everywhere...except in places where it's considered normal to not wear shoes, such as in the house, at the beach/pool, swimming, bathing, sleeping, etc. In those cases, Alice puts on a pair of heavy combat boots.
Alice is obsessed with shoes, and does not like going barefoot since it means missing an opportunity to show off part of her collection.
Subverted: Suddenly Alice starts going barefoot. One of her friends asks he if she has decided to become a barefooter, so she answers: "As a matter of fact, no, I just lost a bet... and it's starting to get annoying!".
Double Subverted: Suddenly Alice starts going barefoot. One of her friends asks her if she has decided to become a barefooter, so she answers: "As a matter of fact, no, I just lost a bet... but it's not that bad!" After reaching the bet's deadline, Alice realizes she has actually enjoyed it, so she decides to go barefoot more often from now on.
Alice has a Split Personality disorder, so, much to her annoyance, her disdain for shoes varies depending on which personality takes control of her at any given time.
Whenever she can, Alice does not wear shoes. However; Alice puts on shoes whenever she feels she really needs to. (To look professional or for safety purposes.)
Alternatively; Alice normally does not like shoes; but there are a couple pairs of shoes that she loves and whenever she is wearing seen wearing shoes is always wearing those.
Alice hates the thought of going barefoot, but a friend manages to convince her to try it for one day. Alice realizes she likes it and starts going barefoot everywhere. Then she injures herself and refuses to go anywhere without shoes from that point forward... until she realizes that she misses the barefoot lifestyle and promptly ditches the shoes again.
None of the series' characters are ever shown barefoot at all.
Alternatively, all the characters of the series go barefoot all the time.
The entire cast are nagas, mermaids, or other legless beings and therefore don't have feet.
Enforced: "The actress playing Alice is a real-life barefooter, so early in the development she asked if this trait could be carried into the character. We didn't have any objections about it, so it was quickly implemented into the story."
Lampshaded: "Should I ask why Alice isn't wearing shoes?"
As a wacky new folk joins the True Companions, Alice adopts this quirk (among others) as a way to consolidate her status as the group's greatest Bunny-Ears Lawyer.
Alice develops a bitter rivalry with a woman who is well known for being utterly shoe-obsessed, so Alice starts going barefoot to set herself apart from her.
Alice becomes angered at the business practices of a certain shoe company, so she begins going barefoot as a form of protest.
Exploited: Alice's archnemesis, well aware of her adamant disdain for shoes, decides to cover his home base with several traps and hazards that would be extremely damaging for an unshod person, like scorching metal plates, acidic goop, sharp spikes, and chewed bubble-gum.
Defied: Despite her affinity for walking without shoes when she was a kid, Alice's parents actively discouraged her to prevent this conduct, up to the point she cannot do it anymore due to a Pavlovian response.
Discussed: "You should know better to not provoke a perpetually shoe-less girl; more often than not they can kick your arse harder than those clad in heavy boots!"
Alice's decision of going without shoes is put through several hard tests and hazardous (but plausible) environments as a way to explore and show the risks of it. In the end, she gets a Game-Breaking Injury that permanently dissuades her of ever trying again.
An alternative deconstruction of the Bunny-Ears Lawyer type of barefooter: Alice is told that it doesn't matter how brilliant a lawyer, doctor, or detective she might be... her law firm/hospital/police department requires its employees to wear shoes, so if she wants to remain employed there, she'll have to suck it up and lace 'em up.
Despite the injuries she gets by walking barefoot, Alice remains firm on her decision, and starts putting herself consciously on tests to get stronger. In the end she's capable of feats of skill and endurance that her shoe-wearing companions could never match.