My town has 5 Libraries (includes 'Childrens'). That is a lot of paper books.
Overdrive offers a POOL of e-books that member Libraries can draw on.
If I understand, the depth of the pool (number of copies) is by per member Library (by the contract) There might be 3 copies of a title available here for locals to draw on, while the next town over only can draw 2 of those. (there are only 3 books-licenses in the whole system)
Think of the device (DRM) licensing chaos if every library used a different provider
