I came across a post on Farcebook the other day. It was a pic of an older, retired gentleman who went out weekly with his wife to the local diner, where he sat and counted semis, pickups and motorcycles that went by as he and his wife ate breakfast.The comments were filled with "Autism didn't exist back in the day". Well, hate to say so, but it did. It just went undiagnosed in most folks, as they were extremely high functioning. The only time autism was diagnosed in the past, it was only in more severe cases.
There is also the possibility of natural selection, as like people congregate in similar jobs that they are all good at, like tech jobs that have a lot of repetition.