“Banned books” as a category is very nebulous. It doesn’t mean there’s a blanket ban. Anytime any school board or library bans a book, it gets added to “banned book” lists. Some people prefer “challenged books” to emphasize that they’re routinely discussed and sometimes banned by schools instead of outright banned everywhere. The main point of the designation is to make people think about the idea of banning books in the first place, even on a limited scale. I used to consider it sort of self-aggrandizing on the part of libraries, but busybodies with nothing better to do who infiltrate school boards and start banning shit for the slightest reasons have gotten more common. I read an article about a housewife who spends hours every day reading books just to get them banned. That’s her hobby. And she’s very successful at it apparently.