The Netherlands:
Here is a whole page of what themeparks accept the 'autipas' or a medical certificate, and what perks you get.
Welke dagjes uit zijn Autisme proof? – Uitmetkorting.nl Bespaarwijzer!
I had no clue we had such a thing. It's nice for it to be around for those who really need it. And whilst the discounts are nice, I do think the price is a bit steep to own a card, which I might only use incidentally (most likely only as a sort of "proof" when I have another run in with the cops)