I dont believe teachers or parents to be qualified for such diagnosis. It could be that the kids are angry, annoyed, or annoying, and people think it's autism because they saw one once in a movie. Remember that adults are not very smart in general.

Another theory could be that those 70 years old people are boomers that have been spanked a lot and are more quiet compared to kids whose parents let them do anything (too much freedom and not enough education).

Anyway, I wouldn't trust people to judge anything medical. My boomer parents say stupid things most of the time, yet they do it confidently and think their opinion is the only valid one.

A dumb opinion would be that not caring about others and saying stupid stuff is "autistic," are all the boomers autists after all? See what I did?