I see it all the time. Some people are afraid to approach him so they just ignore him. But he really responds to people who include him and treat him like a human being rather than nonexistant.
When my brother was diagnosed as autistic, the doctors advised my parents to institutionalize him because they said that he'd never know them. What utter bull that turned out to be.
One of the reasons that we see autism more often today than we used to is that there was a time, not so long ago, that most of these children were hidden away in institutions and never seen or heard from again. I thank God that my brother didn't suffer such a fate.
Also, I think that autism is probably over diagnosed. I think that it's what doctors refer to as a wastebasket diagnosis, which means that they don't know what the problem is but they have to call it something, so they'll call it autism. That is not to say that autism doesn't exist; it does. I think though that some people who get labeled as autistic may not be. I will admit that that is just my opinion.