It probably depends. If you're wheelchair bound and are unable to move into a vehicle unassisted you're already utilising wheelchair taxis, not normal taxis, so it probably wouldn't apply in those situations. Refusing to have a guide dog in the car is problematic though, as they're permitted pretty much everywhere and are quite well trained. It's not unreasonable to require drivers to take a guide dog if a blind person hails a taxi, unless they're allergic, so why should ridesharing services be permitted to do so?
In cases where it doesn't require much, if anything other than an attitude change, to support disabled people, it's more or less a no brainer. In other cases, if it should depend on the circumstances. If a person can't change the thing about them that's causing the issue (e.g. in this case, their disability) then requiring businesses to make reasonable changes to accommodate them is perfectly ethical. They're still human, and should be given the best chance to lead a normal life if they desire it.