Ah, but these are library books. Therefore, they are books that people quite like enough to pick up and read once or twice, but are not so fond of that they actually want their own copy. I think this may explain the lack of Pratchett and Rowling, for example.

I used to try to borrow Pratchetts from the library because I'm not actually that huge a fan, but the new ones flew out and didn't come back for months, so I resorted to buying them instead.

Borrowing Tolkien from a library is vexed with woe, because the three books can be borrowed independently and the one you need is *never* there. The most ardent library enthusiast, having read to the end of Two Towers, will surely crack and buy ROTK rather than wait for some other dilatory person to bring the end of the damn book back.