I see that a lot more often these days, especially in restaurants. You just pick an unoccupied room, lock the door behind you, and it becomes either a men or women's room at that point.
This is actually the way it works in private homes.
As a man, I prefer this, because I hate being in a shared men's room when some other slob is taking a crap in one of the stalls and really stinking up the place.
LOL. Even worse … when some other slob is taking a dump, stinking up the place, and carrying on a conversation on his mobile phone. :-O