In my town we banded together with the town library to cycle through books that are otherwise going to be thrown out into the little libraries we have. Someone (me) just had to build a backyard shed big enough to store the “stock” to free up the big library and the librarians are more than happy to chip in a few hours a month to manage it (we have a vibe coded app that integrates with their system to make it easy). Since the library prefilters their collection for us, the vast majority of the books were good to great, they just hadn’t been checked out in a long time.
It ended up saving a whole collection of rare books about obscure SoCal history that were going to be thrown away, because someone got interested in a book from a little library and started checking them out for the first time in years.
As much as I hate it, when discarding books, libraries really should have a policy of checking values/quantity of used copies for sale, and anything past a certain threshold or which they cannot find a copy of for sale, should be put up for sale.