The biggest issue with scooters/wheelchairs (and even strollers) onboard are the people who aren't used to using them pretty much running into others. Space onboard the ship is more limited. And then there are the people in those scooters/wheelchairs who seem to feel as if, just because they are in a scooter, they get priority in the elevators and just barge on in, even before others get off.
Of course, the same can be said for ambulatory people cutting in front of those in scooters/wheelchairs just because they can.
It goes both ways.