@ John Taylor
It beggars belief that we can put a person on the surface of the Moon, yet we cannot design a public toilet which is physically impossible to vandalise.
(My suggestion: have French-style squatting toilets -- after all, it's only the same as what you'd have to do anyway otherwise -- so no seat to rip off and also providing a handy floor drain; flushed from the main, so no cistern to break and flood the place, and entered via a labyrinth, so no lock to break. This probably can be improved upon.)
Public toilets should be funded from general taxation -- after all, taxes are the subscription charge we pay to live in a civilised society.