Another part of that trend that I've noticed of late is people calling piss "pee" and shit "poo" or "poop". Just like you did when you were a 2-year-old and Mommy said you had "poo poo diapers" that needed changing.
"pee" and "poop" are like the base terms for those two things. With "piss" and "shit" being the crude terms, and "poo" or "wee" being the more childish terms. This is the most stupid conversation I've ever had on this website.
Oh, that goes back a long ways, and goes across cultures too. It's a human thing, not an "American" thing. Maybe you can find some culture somewhere in the world that unironically hangs signs that idiomatically translate to "The Shitters ->", but it'll be the exception rather than the rule.
I don't think anyone really associate the the "rest" in "restroom" with resting. May as well call it infantile to call it a "bathroom" when only children take baths.
Right, I resist calling it a bathroom in places where it won't actually have a bath. Guess I should start asking at restaurants where the water closet is?
I'm surprised at this, as in my experience, the overwhelming trend in north america is to avoid talking about bodily functions at all costs, nearly to the point of denying they happen.
The words they use after they break this nigh-impenetrable barrier are usually codified in the most non-offensive ways possible. Someone having a conversation about "shit", for instance, will have a far more uncomfortable audience in North America than someone passively mentioning the existence of "poo" to a group of people. Often, the very subject's focus in a conversation will make listeners question the mental health of the speaker (seriously).
TL;DR - The culture around bodily functions is way crazier than what we call them.
I've noticed this, and it is actually a pain in the butt (minor pun intended) because when you try to book a hotel room or want to look at a home to buy/rent online, they almost never ever include pictures of the "restroom." Even if the size/functionality is a legitimate feature that you're paying for.
Fortunately with travel sites like Tripadvisor often include photos from your average tourists who didn't get the memo about "never take a photo of the bathrooms ever!" and thus you get to see what you're in for with the accommodation. There's no alternative with home shopping, other than physically visiting the place.
Fun Fact: The sole reason North American women discuss menstruation for more than two sentences is because they're wanting to make the man/men sitting near them uncomfortable.