Those of us of a certain age (read: old) still recall standing in line at the bank of copy machines in the school library, quarters in hand, waiting to copy a few pages of a key piece of research found in the stacks. Those noisy machines have now largely been replaced by coffee shops and smartphone recharging stations ... as have, in many cases, the library stacks themselves.
Perhaps fittingly, when Google decided in the early 2000s to digitize the world’s books, it began by partnering with large libraries to copy portions of their collections, including many that are now out of print. Those libraries themselves generally held no copyright interest in the books they provided to Google, but rather held unique, expansive physical collections of books that made them a good fit for Google’s project. Partnering with libraries (rather than, for instance, buying up books from bookstores) was also clever on Google’s part: It put Google in league with academic and research institutions, who are more often on the fair use side of the copyright infringement equation.