Theft of library materials is an unfortunate but common problem. It’s just the reality of the world I which we live in, that books that contain certain knowledge that is considered by society at large to be embarrassing or controversial will disappear from a library shelf for a verity of reasons.
Maybe you’re too embarrassed to be seen checking out a book of photos by Mapplethorpe of big black cocks. So you take an exacto knife and slice out a dozen or so of your favorite photos, set the book back on the cart to be reshelved and walk out with your head hung low.
Perhaps you don’t think that a library should have that book by Jock Sturges or Richard Dawkins. So you steal it. That way, no one will be able to check it out. As if that will make Jock Sturges or Richard Dawkins go away, stop taking naked pictures of preteens or writing about evolution.
A common practice among some church groups is for their members to go to the public library, check out all the books on witchcraft and paganism. They keep them the full amount of time possible, renewing them as often as they can and returning them, only to have another member of their Bible study group check it out five minutes later. That way, no impressionable teenager will be able to read that particular book and learn anything but what they hear in Sunday school or in their home school class.
It doesn’t work of course. Libraries will eventually replace those books. They will get in the hands of those who are curious and want to read them and appreciate them. So, stop steeling our fucking books, umkay? Or else a gang of pissed off librarians will come for you.