Didn't Google Books have the same policy with libraries? We scan your books and in exchange... of course we don't give you the scans.
Full disclosure: I joined Google in 2005 when this was still an active project, and in fact walked around GWC-3 and saw the Yellow Badge people (great symbolism there) taking their breaks. These were contractors who actually scanned the books for Burger King-level wages, and whose badges wouldn't even let them into the micro-kitchens.
Anyhow, I don't know if the University of Michigan (early volunteer) was supposed to get the scans. Supposedly, the whole world would. That didn't happen and you can read [1] for details.
As of 2015, at least, not even a Google employee could get at them. I was told I could go to someone's desk and read the book on their computer if I really wanted to see it (this was for patent research).
[1] https://www.theatlantic.com/technology/archive/2017/04/the-t...
For the general public HathiTrust is like Google Books with worse search and worse UI but more books readable in full. Sometimes I search Books and then go over to HathiTrust when I find that Books has unreasonably restricted viewing of some search hits.