The trigger for the avoidant behaviour in PDA people isn't socialising, many of them including me very much enjoy socialising (although there may be stressed around social expectations). It's anything that's perceived as a demand (i.e. something that must be done, or is expected). For many people with PDA (esp. children) this can be things as simple as putting their shoes on or brushing their teeth. It may also include activities that they otherwise enjoy.

(Side note: if you're from the US, then you may see much more forced socialisation. In europe, quiet people are allowed to be quiet to a much greater degree. It's not seen as rude to be quiet here)

Wow, we don't quite know what autism is (don't know if it is a spectrum or a set of separate conditions) therefore it becomes possible to assign the label to almost every condition. I think that's amazing.

And I was unaware that children with foot infections, say, stubbornly refuse to brush their teeth as a result as you seem to suggest. (Sarcasm for Sarcasm.) Many children would rather avoid brushing their teeth. Few children are radically opposed to tooth-brushing, say to the point where they'll skip a meal to avoid it. I don't think you understand how unusual the behavior being discussed, is.

I'm totally open to this being a diagnosis. But I think the point is more that a kid with a foot infection who refuses demands would probably be called "independent". Stubborn, even. But it wouldn't necessarily be medicalized.

There was a recent study on ADHD and birthdates; the upshot was that kids on the younger end of the age spectrum are medicated for ADHD more if they're young for their grade. Which implies that some number of kids are medicated more for "teacher inconvenience syndrome" than any real disease.

There's a long history of medicine treating different as bad. (The formal academic term is "medicalization of deviance".) So I think it's worth being a bit skeptical that traits that teachers and parents might inconvenient are diseases on the order of foot infections. Rather than, say, how homosexuality was medicalized for decades.