> Reasonable accommodation isn’t significantly onerous in the vast majority of cases.
You are correct that a reasonable accommodation isn't particularly hard in many cases.
The disconnect in communication here is that you're thinking in terms of a reasonable person.
Unreasonable people exist.
There are unfortunately some disabled people that would refuse to be satisfied by almost anything you provide them. The ADA lawsuits don't magically vanish just because you try and be reasonable and they refuse to be satisfied in turn hoping for some payday.
The vast majority of disabled people are probably thankful for the accommodation, but it just takes 1 ambulance chasing jerk to pursue a dumb case that sinks a business.