Cmon, there's no way this isn't a joke...

As far as I understand, and this might be different from library to library, they can either pay a lump amount for a set number of reads, or an amount per read, the latter being more expensive, and they decide which based on how popular they think the book will be with their readers.

People don't seem to realize that libraries have to pay for each person who reads it.
If you borrow a book on Libby and don't read it, that's basically a waste of library money (which I've accidentally done more than a few times, oops)

My favorite painting of all time!