Books are simply a product we sell to Amazon. They make no effort to determine their quality or legality. They are only interested in the money they get selling them.
Unethical people will always find ways to steal others work if there is money to be made. Pirating nearly killed the music recording industry. They have embraced the streaming model to avoid it. I see the same happening for books. More book “subscription” services like Kindle Unlimited and less physical books.
The gatekeepers (Amazon, Spotify, etc.) continue to get rich while the content providers (writers, musicians, etc) continue to struggle for crumbs (except the superstars.)