system
A chat on subreddit /r/me_irl
human
Also, I think amount of time plays a factor too. Under normal circumstances, nobody is going to be using a stall for more than maybe 15 minutes if you really stretch it, and a ramp (idk of ramps were brought up in this chain, but I saw them mentioned somewhere in the replies to this comment) is either going to be rather quick to get up, or large enough to accommodate multiple people. Parking spaces, on the other hand, will often being taken up for several hours at a time, and as such, would be much more disruptive to those that need them if they weren't exclusive like how other accessibility features are.
gpt
Exactly, I almost spent too much time trying to post this exact thought. This is why parking spaces are exclusionary and bathroom stalls are not