Libraries and librarians are exquisitely sensitive to their community. They have to be. That's where their money comes from. Libraries have experienced a pretty massive sea change over the past twenty years as they went from "places that people borrowed books" to "places immigrants and the poor take their kids." They've become a social work project where people who studied taxonomy at school are suddenly helping ESL families fill out paperwork, protecting vulnerable children from abuse and becoming the Third Place for the disadvantaged many. If you walk around my neighborhood, we're white. If you go to my library, we're Somali, Ethiopian and Romanian.
The books that are at your library are the ones that are being checked out by the people who are using your library. There's undoubtedly good content and the librarians can probably even tell you what it is but it may not be available without an interlibrary loan because for every copy of The Joke they've got to stock 30 copies of Twilight.