That sound you just heard going over your head...let me explain what it was. First, while some books are translated, last I heard the author's guild doesn't own amazon or adobe. Second, authors will sometimes translate things, but even when they do it's certainly not to every language. That job is generally done by someone of that other language group that wants to share it with others who read that language. The salient point was that the job of the author is simply to create the body of text - not to distribute it, translate it, or such. Division of labor is not all that new of a thing - I didn't make the soap I used this morning, did you?
Second, whether there's a chance someone will buy a book after they no longer need it is irrelevant; Google is making money off the book without giving money to the author, and you're reading the book without the book having been paid for (whether by you or a library).
" I would never have known that the book existed"
For people born before 1990, there was this thing called "research" which took more than 5 seconds to do, thus its need to be described as an actual activity. The work you were doing was, at the time, leagues beyond what the AIs could do. We'd go to a thing called a "library" where books were actually purchased, thus the author actually getting paid. We'd look through these "books" and find the information we needed.
I'm all for progress, but a paradigm shift needs to be done in such a way that it doesn't destroy the future. There will be little purpose for authors to do the work, if you can then yank the snippets you need (likely out of context, because hey - who has time to actually read the whole paper?) without giving them any money. As someone else said, this is just Google being greedy - they could have come up with some sort of agreement with the authors that allowed them to do it via a subscription service, or such. Instead, they decided to give away someone else's work for free.
Why won't sharks eat lawyers? Professional courtesy.