Also the NHS ADHD/ASD services are completely overrun. Waiting lists for children can be more than 5 years long.

In order to cope with this the NHS has spun out much of the ADHD/ASD assessments through the Right To Choose program (well, in England at least, Scotland/Wales/NI are on their own), which means that private companies are being paid by the NHS to make up the shortfall. Ref: https://adhduk.co.uk/right-to-choose/

Some people say some of the private companies are too lenient with their diagnoses. Some people say that the NHS is too strict with their diagnoses. I'm sure the real answer is somewhere in the middle.

As you say, the sharp rise in diagnoses is probably more due to people become more aware, with less stigma attached, and having better access to assessment.

Shit like _Rain Man_ almost 30 years ago or, more recently stuff like _The Good Doctor_ really don't help though, as those just reinforce the negative stereotypes of Autism.

ADHD also has a strong genetic component with heritability around 75% according to various studies. My parents (undiagnosed but one definitely ADD+ASD) have 1/4 children diagnosed (and another 2/4 almost certainly undiagnosed, one neurotypical), and 6/10 grandchildren diagnosed (the other 4 are neurotypical).

Who knows, in 20 years time mainstream schools could have switched from 20% SEND and 80% neurotypical to 80% SEND and 20% neurotypical.

In my family it's been difficult for some to accept my sister's autism diagnosis because Rain Man is the prototype of autism they have in their heads. Younger family members who have been exposed to classmates who are on the Autism spectrum have been accepting of the diagnosis as their image of autism is very different than the one older family members have. Good thing is despite some not believing in the accuracy of the label, they're still supportive of her.