"I don't understand, medical reasons aside, how people are so unable to manage their bladders". Some bladders just don't stretch like others - also some people have very bad discomfort compared to others. I only know this because I once had a very stretchy pint-a-piss bladder but after an operation am now the proud owner of a half-pinter, which, if stretched enough, causes the sort of pain as to make pissing in a bush the least of my worries. Assuming there's no loo available, of course.