"Book banning" isn't actually banning books in America because the 1st Amendment's protection of the freedom of speech prevents any and all book bans. Instead, "book bannong" is a grossly exaggerated phrase used by a small fraction of people, usually of a liberal persuasion, who wish to incite fearmongering among the populace, usually over books the fearmongers support that are very inappropriate for the age groups they are intended for, specifically regarding graphically sexual material. Removing or restricting children's access to these books, even if merely requiring parental notification and consent for their children to read the books, comes nowhere near the idea behind actual book banning.
"Boy, I gotta tell ya. Conservative Christians don't want middle schoolers reading a book in class describing two boys sucking each other's dicks. Those fundies sure love book banning."