‘murica

When I frequented small cafés before the epidemic lockdown, it was typical in San Francisco to get frequent impatient door-knockers.

Part of the problem is the lack of publicly available restroom facilities. Shopping malls often might have two restroom pairs, usually at the food court and by the movie theater, and then one each at thr major department stores, typically hidden by the changing rooms.

I cannot say how this compares to other towns or other nations, but designing public lots in The Sims 2, I quickly learned to make sure there were facilities a short walk from everywhere. (Also skip the sinks and install showers, since sims dress and undress with a quick spin)

Idk about OP but where I live most public stalls do have indicators but not all of them. Often custom bathrooms for places like restaurants tend to be missing them since they're to some degree custom designed to match a certain aesthetic and I'm guessing in those cases indicators are easily forgotten or just left out of more niche bathroom stall door designs.

I wouldn't be surprised if this is also an issue in older bathrooms with older stall designs because I remember indicators being less common when I was a kid. But I usually knock if I'm checking a stall like that and don't try to look underneath until I've tried less invasive measures. Honestly usually you can tell just by looking at the shadows on the floor and seeing if there's any movement or not, without having to bend over to check for feet.

Wait till you get a load of the accommodations in much of the developing world. I've had some real adventures during my travels over the years.