When I first landed on the ROC, I never saw a case of autism, or one I'd suspect, anyway. But things have changed a lot now and in the last two years I was there I saw several, taught several, kids with autism. But there are many reasons for this apparent increase, IMO.
Firstly, I think that attitudes have changed a lot. Taiwanese people as a group are more educated, and more accepting of differently abled individuals. There are still a LOT of jerks out there, but attitudes really are getting better. My friends and I used to remark that you never saw a mentally or physically challenged person outside, but now this is common and there are even attempts at building adequate infrastructure for wheel chairs, canes, and service dogs.
Secondly, pertaining to Autism specifically, the diagnostic process has changed and it is not considered to be "a" disorder, but a spectrum of symptoms and severities. This means that more people are diagnosed as autistic in some way. This is good in places where an accurate diagnosis opens doors to better services, and unfortunate where it's simply a label that a person will be stuck with for the rest of his/her life. But this new spectrum diagnosis is being credited with a marked increase in autism cases all over the world.
Finally, I personally believe that our environment may be partly to blame for a real increase in instances of this disorder. An over controlled, over vaccinated, over modified food source, more chemicals in everything, pollution. It's not beyond me to believe that this has something to do with it.
In Taiwan, I feel like the practice of buxibans accepting autistic kids is very unfortunate. This is because these kids actually DO need trained teachers and care givers to thrive, but they can truly thrive if they have appropriate teachers and appropriate goals. The buxibans won't turn them away because money is money. Buxiban teachers usually aren't even trained in teaching, much less working with/teaching autistic children. It's always the kids, and their classmates who suffer because someone out there sees dollar signs when he looks at kids.