I am neither disabled nor assist someone with a disability; however, I am an architect and specialize in ADA compliance, and would like to comment on the architectural problems that you encounter, especially in US cities. The Americans with Disabilities Act was passed in 1991, and since then, extensive changes have occured in the US. Any new or renovated building had to be brought up to the code. This code includes the speed at which elevators close, the height of the call buttons and the operating buttons, the size of the elevators, as well as things like the reach heights of the towel dispensers in the restrooms. I would think that the newer ships would be more accessible than older ones. I would also guess that ships with US interests would be more aware of accessible issues. Europe and Canada are oblivious to any kind of accessibility codes, or considerations. It is up to the cruise line to insist on the design. For legal ramifications, a person can report a violation to the Dept of Justice. About the only way something will get done is if you sue someone. In Texas, it is much easier: we have ADA police! You just have to make a report (on-line) and it gets investigated and SERIOUS fines are imposed.
On a positive note, the ADA guidelines are being updated, as of the end of this month, and will become even more stringent, with new requirements for multi-housing, among many changes.
If anyone has an ADA question, I would be happy to answer it for them, if I can.