If you see someone in a wheelchair stand up or walk, just keep your mouth shut. They either were prescribed that wheelchair and their insurance agreed they needed it, or they became so desperate for the mobility the chair would provide that they paid a lot of money out of pocket (because they don’t have insurance or they have a shitty ableist doctor or whatever).
It’s estimated that around 85% of full time wheelchair users can stand or walk to some extent. Think of it like glasses: the majority of people who wear them can technically see without them, but they reduce pain, improve the quality of the wearer’s life, and enable millions of people to do things they otherwise couldn’t. A wheelchair is no different. In fact, even part time users legitimately need their chair, just as people who need reading glasses legitimately need their glasses. In addition to paralysis, some reasons for using a wheelchair include pain, fatigue, fragile joints/bones, vertigo, and many, many other debilitating symptoms.
Using a wheelchair is already stressful enough as it is, thanks to iffy accessibility. Please don’t add to a disabled person’s difficulties by calling them a faker.