Given that the exact same question is the current top post but for driving instead of transit, I feel this question was needed.
My answer: I saw some guys hooking up a Raclette Grill to the outlet in an otherwise empty German intercity rail waggon. They had it unpacked in one of these 4 person seats with a small table. No idea if that could work or if draws too much power from the board net. I just headed on to the next waggon.
When you buy products that are deemed sensitive, such as condoms or tampons or hemorrhoid cream or whatever it may be, they also put that in a paper bag instead of the regular bag so that no one can see what it is.
Of course, I found this to be counterproductive because that means you know that person is carrying something “sensitive”.
Maybe with books, that’s why they wrap all of them?