Autism is a racket. It's enormously overdiagnosed in the US, and the rest of the world is always eager to adopt our diagnostic criteria and methods.
Read a dead-tree encyclopedia article from around 1970. "Autism" was an extremely rare neurological condition affecting fewer than one in one hundred thousand children. It was the label used then fur a specific sub-category of profound mental retardation. It was fur the children who never learned to speak or dress themselves or feed themselves, when they also displayed certain very specific, very unusual repetitive behaviors.
Since around 1990, though, does al little boy struggle with learning to read? He's got THA AUTISMS! Does he learn to read earlier than the children around him? AUTISMS! Is he shy? AUTISMS! Is he gregarious? AUTISMS! Does he talk a lot? AUTISMS! Does he not have much to say? AUTISMS! Is he really athletic? AUTISMS! Is he clumsy? AUTISMS! Is he happy? AUTISMS! Sad? AUTISMS! Sensitive? AUTISMS! Oblivious? AUTISMS!
There are a few different things driving this, and society follows the vector sum, so to speak. Part of it is US federal government disability assistance money, which is trivially easy to farm with an autism diagnosis. Befure the kid turns eighteen the funds go to his parents. Cha-ching! Every elementary school gets additional federal money fur each student they have who has an autism diagnosis. Cha-ching! "Autism treatment" is a multi billion dollar cash cow, too, and there are fewer limitations than you think on who can hang out a shingle and claim to be an "autism specialist" and start cashing six-figure government checks.
There are some people who will tell you that it's also political, an extremely feminized psychotherapy field that is made up largely of joyless pinch-faced schoolmarms who really, really hate those icky, icky boys. Supposedly they get off on hanging psychopathology labels on as many as they can, while narrowing the definitions and criteria fur Borderline Personality Disorder so as to keep themselves outside the lifetime-label dragnet even as they diagnose each other with "bipolar disorder not otherwise specified" and "complex post-traumatic stress disorder," gobbling Xanax and SSRIs the whole time just to cope with ThUh PaTrIaRcHy. I am less convinced of this. The money trail is readily observed and confirmed. No shadowy conspiracies are needed as an explanation. Though if you've ever dealt with headshrinkers, you may have noticed certain trends and tendencies that may incline you to find portions of it plausible.
Also, I like trains. https://youtu.be/5DjOL2we8ko