> Because the odds that a regular disabled person would encounter 200 unique buildings over a year that they couldn't access because of their disability seems quite slim.

I would guess the opposite, that 200 buildings seems low for what a person might encounter in a year that failed to be accessible. That's basically saying, "It's a roughly 4-5 buildings a week" which absolutely seems in the realm of possibility to me. Especially in a older part of town.