The college residence where I lived while 5 years at the Australian National University had co-ed restrooms in the living areas. (4 co-ed restrooms per floor, with 4 stalls in each and 4 enclosed capsule-style shower cubicles in the adjoining room.) The admin block had 4 single-sex restrooms, 2 for males and 2 for females. The female restrooms had just one stall in each, no showers - not sure of the situation in the men’s restrooms!
You go in, you enter a stall, close the door behind you and lock it, do your business, exit the stall, wash your hands and get out. Every person, male and female must void waste. As long as everyone is being well-mannered and cleanly, and not trying to peek over or under the stall walls, there shouldn’t be a problem.
Likewise, if one needs to shower, you enter the capsule, lock the door behind you, shower, dry yourself, don clothes or a modest robe and return to your room.
The only problem I had with the arrangement was the tendency for some males to leave their stall door open when urinating. This is clearly unacceptable in a mixed sex environment. Men may be used to being able to see each other when urinating in public urinals, but it is not good etiquette in mixed environments. I highly doubt their mothers considered it appropriate behavior at home.
I also considered it inappropriate to hold conversations between stalls (as some females were wont to do,) particularly when that conversation was not appropriate to be heard by the opposite sex.
But surely people adhering to minimum standards of courtesy should ensure there is nothing improper whatsoever about the use of a co-ed bathroom.
