The problem I see is that you are a responsible parent but many are not and think that if a book is available in a libary or at school then it will be OK for their child whatever age.
I can understand the concept where certain people fear not their own children being exposed to the material but those who do not have parents who understand what is out there and maybe cause distress or put ideas into their children’s minds that are not desireable. Too many people trust that if it in a school or a library it is OK. Also there are parents are so liberal minded anything goes and freedom of expression is everything whether it is good or bad. Who is going to protect these children.
Okay, so would you like to control what the children of liberals or those you deem as "not responsible" read, or would you like The Nanny State to decide what these children can or cannot read?
Who is going to protect these children.
How about their parents and not you or your Nanny State.