Books are culled from libraries all the time. One Australian university library chooses and destroys books "by stealth", according to a librarian friend who works there. The management doesn't want to deal with librarians' knowledge, grief and rage.
Some libraries sell their discards to the trade, and that's how just last week my newest addition to the family arrived: Everyman's Library edition of Raymond Chandler's Collected Stories (a discard from the Houston Public Library, purchased by them in 2002, but still in perfect condition).
6 for $2
The four-book picture above is the latest haul from our local library. These wonderful classics have lived downstairs in stacks for years, so would only have been checked out if found on the computer. At the library, the discard table seems to waft some irresistible perfume. Readers leave it laden with books that for the first time in years, soon feel fresh air on their pages, and dropped into their cleavages, fresh crumbs.