It's what's happening in some secondary schools in Fife - sinks are open to the corridor - there's a space where a door should be. (The door frame is there...only the door is missing.)
In one school built in the '80s they achieved a similar level of inconvenience for female pupils by putting in large windows which allowed you to see into the sink area.
It's supposed to stop bullying and vandalism...
It does not stop bullying and vandalism.
Moreover, in new build schools staff were initially expected to share facilities with pupils. One school circumvented this by declaring that one set of toilets was for staff only. Another told staff to use the disabled toilets.
The solution (If there was one) depended on the HT. There was one male HT who refused to set aside toilets for staff. It was later realised that he was making use of a toilet "for visitors" which was very close to his office.