I never said all Ubers should be wheelchair accessible. I was responding to your assertion that wheelchair-bound customers should bear all the cost of their accommodations.
Currently, in most cities, a certain number/% of taxis are required to be wheelchair-accessible. It's a bare minimum, usually with wait time well in excess of what the rest of us would consider reasonable (DC states it averages 45 minutes, but I can call a cab in 10-15 minutes notice or hail one on the street in less time than that).
If there was a market for equivalent service for wheelchair-bound customers, it would exist already. The market simply doesn't exist, at least not in any way that makes financial sense. So we have regulations to force it.
Having a blind family member who encounters similar issues on a daily basis, I'm totally fine with socializing the cost of her accommodations. To do otherwise would just be greedy and mean.