My three year old is very independent. As I'm potty training him he wants to get on the potty all by himself, use toilet paper (even though he doesn't need to) and flush the toilet all by himself. I could imagine if he was in a wheelchair he would be just as independent and stubborn.
The new ADAAG does give provisions for children's facilities (like day cares, elementry schools, and even shopping centers). They have requirements for grab bars, for different heights of things and even knee clearances at sinks and lavatories.
There have been arguments against having a separate toilet or accessory for kids, which goes something like this:
" There will always be someone there with them". "What does a toddler care who puts him in the potty?"
Obviously not anyone who has dealt with a two or three year old recently.
But even if it's for a child who allows their care takers to do things for them without a fuss, it is all about the dignity and quality of life for the disabled child. Just because they have a disability does not take away from the fact that they are normal kids with normal desires, especially the desire for autonomy.
Texas already has these rules in place, and we follow them stricly. And now with the new ADAAG almost coming to effect, this will be the law of the land.