> I don't think this invalidates the broad observation

The word you're looking for is stereotype. There's lots of harmful and inaccurate stereotypes about all groups of people out there, and polite society generally frowns on using them as a form of bigotry.

> Perhaps there's a critical time in development when socialization is necessary and there are other venues than public school to remediate this.

There are tons of opportunities for this sort of thing, in the form of non-school youth groups such as 4H, sports teams, scouts and so on.

In fact, actual in class socialization is frowned on or punished in most schools. It's the in-between time and extracurriculars when that happens most anyway.

> The word you're looking for is stereotype.

Sure, but that doesn't change anything. That some people will be unfairly characterized by this is an unfortunate byproduct of being born a human.

> There's lots of harmful and inaccurate stereotypes about all groups of people out there, and polite society generally frowns on using them as a form of bigotry.

Only the bigoted forms :) stereotypes aren't going to disappear out of inconvenience

> In fact, actual in class socialization is frowned on or punished in most schools.

I've never heard of a school that could combat socialization in any meaningful way.