The question is, does Uber have training in place on what rights a disabled passenger has? Do they discipline or dismiss drivers who receive disability complaints?
It sounds like Uber's response has been that it has no duty to support or enforce the ADA.
Uber is forcing taxis out of business. One of the reasons that taxis are regulated is that they are bound by law to transport the disabled. If we are going to let Uber put them out of business, then we have to aggressively protect the rights of the disabled.
In any case, in many locales it's almost entirely unheard of to street-hail a taxi. To name two places I've lived, in Boston and Silicon Valley, you always need to call for a taxi, unless you happen to be staying at a hotel in a downtown area.
However, they should additionally be barred from picking up clients on the street.