I think this explains at least some of it. In my childhood (1970s) as best I recall, these kids were hidden away. They went to separate special education schools or a separate classroom in the main school and didn't really mix with the rest of the kids. Today the attempt is made, for better or worse, to mainstream everyone as much as possible.
It still feels like there is more autism today compared to then though. I would guess that it's some combination of more people waiting to have kids until they are older, environmental factors, mania about cleanliness and sanitizing everything, maybe social factors such as putting more kids in daycare at a very young age, IDK. I'd say the same thing about asthma and food allergies too, seems that half the kids today are allergic to something, need inhalers, etc. It was unusual among my friends as a kid, at least I don't remember it being common.
It still feels like there is more autism today compared to then though. I would guess that it's some combination of more people waiting to have kids until they are older, environmental factors, mania about cleanliness and sanitizing everything, maybe social factors such as putting more kids in daycare at a very young age, IDK. I'd say the same thing about asthma and food allergies too, seems that half the kids today are allergic to something, need inhalers, etc. It was unusual among my friends as a kid, at least I don't remember it being common.