Several people I know have autistic kids. Schools don’t want the kids or know how to handle them.
ADHD is much easier to diagnose and would be the choice of schools motivated by dollars.
Autism is the new buzz word for kids that don’t get enough discipline from their parents. The parents can’t control these kids so they have to blame it on something. Used to be “Attention Deficit Disorder” now it’s “Autism”. True autism is very rare. These kids are suffering from Parental Child-Rearing Disorder.
There is the diagnosis of autism spectrum. Is your kid shy, socially awkward, has difficulty standing up to bullies? Welcome to the world of Autism spectrum.
Also, a significant number of children who would be traditionally diagnosed with mental retardation are now getting labeled at various medical conditions including autism spectrum. This makes the concept of looking at diagnosis rates over time frought with inaccuracy.