It’s important in the fair use assessment to understand that the training itself is fair use, but the pirating of the books is the issue at hand here, and is what Anthropic “whoopsied” into in acquiring the training data.
Buying used copies of books, scanning them, and training on it is fine.
Rainbows End was prescient in many ways.
That's how Google Books, the Internet Archive, and Amazon (their book preview feature) operated before ebooks were common. It's not scalable-in-a-garage but perfectly scalable for a commercial operation.
The books that are destroyed in scanning are a small minority compared to the millions discarded by libraries every year for simply being too old or unpopular.
Book burnings are symbolic (Unless you're in the world of Fareinheit 451). The real power comes from the political threat, not the fact that paper with words on them is now unreadable.