As an author of over 15 books on Amazon - book Censorship always gets my attention when it is in the press.
The answer the public library offers is to ask your children what they are reading...the person making that recommendation must either be naive or not have children :) since when do our children tell us about the bad things they are reading or watching online?
I have instituted a "Parents Page" with my books that informs parents of subject matter so they can determine if they want the child to read the book.
I have been censored from one church because a 18 year old in the story is dreaming of a girl in a bikini on a white beach...their religion believes bikinis are of the devil so they banned it...that should be their right and I respect that. That is the same reason the yellow banner serves as a warning that my books are Pro-Jesus; to be fair to the parents that do not want their children to read books with Christians seen in a positive light.
Authors should take the responsibility to have a information page specifically for parents describing their view point on content if they want parents to trust what the child is reading.
I wonder what many parents would have done if they understood The Hunger Games from a view point page.