Don't be so sure of that. There is a bookstore in the main branch of our library, and they will take donations for sale, but the library will not place them in the collection (they buy new materials that often come partial processed) and the bookstores generally have limited space to store stuff. My library generally asks people to keep drop offs to 2 or 3 boxes.

Even to Goodwill or other places. I don't care for how Goodwill deals with their profits but I sometimes find good books there for really cheap.

Several charity shops locally now have signs in the window saying they no longer accept books.

They were receiving so many unsellable pulp novels that they were having to pay recyclers to take them away.

Which is a real shame because amongst the mass-market paperbacks I occasionally found gems ( e.g. geological atlas of French wine regions )

Or even a laundromat. Someone will pick them up and start reading them, it's a near guarantee.