Earlier quoted context omitted.
The funny thing with these kinds of "rules" / customs is that you internalize them; I can't even imagine myself taking pictures in the subway... I suppose a UK/US person would never consider it apporpriate to take photos in a bathroom for example.
I'm a US person, and on a recent trip in the US South took photos inside a (public) bathroom on more than one occasion, when I saw something entertaining. Not photos of people, of course, but there were other people in the bathroom on both occasions, and no one seemed shocked or worried. I'm confused about how this aversion to cameras can possibly hold when nearly everyone is carrying one or more cameras at all times…
Exactly, "not of people (in the bathroom)". Would you take photos of people in a bathroom. If you're male, would you take photos of men at the urinal?
Does everyone in Europe avoid using their smartphone except in the privacy of their own home?
No of course not.