Sorry to hear that. I sometimes travel with a special needs girl. She'll be alright the entire day, and then something unexpected happens, and everything becomes a big hassle. The world can be cold and cruel to vulnerable people.
Alas, like you, I'm not one to scream and insist people help us and threaten with lawsuits. I have a feeling that if you caused a scene after your daughter had been pushed down, or even at the first aid office, Disney would've taken you backstage and driven you all the way to your car. If however you continue on as best as you can on your own, you end up stranded alone on a parking lot, nobody aware of the issue, with possibly an unspoken assumption that you should've 'thought about it before'. Nobody sees the problem anymore, or feels responsible.
I have never really solved these issues in my own life.