We don't know that they're not either. As pointed out the fastest method to scan books is to cut the spine and scan the pages, effectively destroying the book.
Is this the place we think Amazon decided to be careful and deliberate about what they do?
Most reporting says they are being destroyed. Page flipping is slow compared to cutting the spine and scanning the pages.
They destroy regular books. This was an intentional order from a rare book dealer. There is no reason to believe they use the same destructive process for books they should know to have inherent value and aren't purchasing in significant volume.
I don’t think we read the same article. None of these books were identified and they said rare can be low print volume or foreign language.