Korea used to work like this, informally. After some years, building owners started putting locks on bathroom doors. Patrons can receive the code upon purchase.

It was one of the little things that made living here more pleasant. It's a bummer it's mostly gone.

Related:

Seoul (and most of Korea) has few or no public trash bins. My proposed solution is to make convenience stores allow anybody to use their trash facilities, as most trash is generated by them. (in Korea, there is a convenience store on every other city block, usually three in close proximity)