I'm really very sorry but I think you might have a limited view based on your own experience.
I've done some searching about institutions nand the kinds of abuse suffered by these children ranges from emotional to physical to sexual from the 80s to the 90s, and I know it will have been more prevalent earlier in the 20th century too but 2 children's homes in Nottinghamshire have popped up. Amberdale and Beechwood.
In the 50s-60s there was a significant amount of abuse coming from Kendricks Hall in reading.
In north Wales, Bryn Estyn as an example, many kids there had no family advocates whatsoever and received a significant amount of abuse from staff.
I am sure if I looked further I could find a whole library of information on abuse scandals for children in homes who have been placed there through disability or poverty.
I could definitely find articles about correctional facilities, many of which will have had many autistic children as young as 10 directed there as their unmet needs and behaviours would either lead to crime or they'd be incorrectly institutionalised as a form of correction for their behaviours and painted as criminals. Borstal for one. Overcrowded, underfunded, abuse from staff, etc.
Children have died in these institutions because of the abuse they have faced.
It sounds like your experience with autistic children wasn't in these institutions. I'm happy that the abuse wasn't universal. But it is undeniable that it did happen.