> with a focus only on books with an ISBN number, the identification system introduced in 1966 So it's not likely to be rare and precious books. It's things which are already in the Library of Congress or its many equivalents. If they're forced by laws to destroy the results of the scans after training on them, as some have implied, that's bad, on the chance there is some actual lost media in there. But if they keep…
There are plenty of rare and precious books with ISBNs.
(EDIT: I'm assuming "precious" means the same as valuable here to make the question easier to answer. In fact, of course, people usually say "precious" when they mean a personal or emotional attachment or cultural importance rather than economic value.)