“Fake autism” is a great way for parents to receive the benefits of having a “disabled child”; I know parents of a “high-functioning autism” child, and I’ll tell you there is nothing wrong with the kid. He just shows the classic traits of an only child who rarely sees his parents (due to their jobs) and is raised by TV. Nothing unusual in his speech or behavior; he just isn’t accustomed to being around children his own age outside of a school setting, and shows the normal attention deficit of TV kids (where the attention span is approximately the length of a commercial). On the other hand, I’ve interacted with autistic children; there is a huge indisputable difference.
It is a spectrum disorder. It could be that the child you think is fine, isn’t. I don’t know, but in cases where the child is highly functioning at some things, he may be clueless in others. There are kids with autism who can do all their homework in an hour, but can’t tie their shoes even after 10 hours of occupational therapy.
It is very cruel to belittle your neighbors and friends who have a kid with autism by not believing them. Of course dx can be wrong, but give these parents the benefit of doubt.