>>I have never even considered peeing in the shower.<<
Me neither - until I was 35. I learned what was actually IN pee and one day in the shower I really had to "go" and suddenly thought, "Why not?" It was a paradigm shift and I never looked back.
When I was in grade school I thought sex was gross too!
Perhaps you are the height of sophistication and erudition, but I will continue to piss exclusively in toilets or behind trees.
Put another way, as urine is so harmless, would you pee in your own swimming pool? Would you pee in your own bath?
I once read a series of jokes similar in style to Jeff Foxworthy's, "You know you're a redneck if...", but these all started, "You know you're a white person if..." The punchline in most of them implied that white people are too anal and uptight. When I got to the one about, "You know you're a white person if you get out of the shower to pee", my reaction was, "yeah, I do that, and now that I think about it, *why*??"
As you say, a paradigm shift. It's the same damned plumbing, and at least in the shower any risk of splashback is immediately washed clean. Plus it saves dripping water all over the floor. But unlike George, it's not something one should do in a communal shower.