When you're pissing in the shower at home it's your shower, its bad manners to piss in someone else's or a communal shower. Or in a swimming pool.
Exactly, its just bad manners, nothing more.
Peeing in a swimming pool is worse.
Urine isnt going to hurt anyone and I, for one, am not concerned about it. At the gym, I walk barefooted to the urinal to pee before showering; if for some reason I need to pee after showering, Ill walk to the urinal, pee, then walk back through the shower to wash off my feet before putting on my socks I dont exactly like the idea of dressing in some other guys piss [or at least, Id like to select my candidate].
I pee in shower at home, more or less aiming for the drain. I love to pee out of doors.