"You own a particular physical copy; you don't possess an abstract transferable 'one-copy license."
There is nothing that says you have to destroy something because you scanned it. This argument has been confusing me since I've seen this pop up.
Edit; despite the above, looking at the court documents from the Anthropic case, this is pretty close to what they were arguing: “we are just transferring the physical form we purchased, therefore it is legal.”
I still dont think there is a requirement to destroy the book, but since there isn’t a reason to store the book and they can’t sell it, they probably just took the cheapest route. It might be worth an argument that they only purchased the right to use the digital copies while the physical copies exist, but I’m in over my head from a copyright standpint
Maybe the law doesn't explicitly say that. But it's easier for lawyers for AI companies to argue the case if they destroyed it. "Look, there's only one copy! We didn't make additional copies!"
It's also probably more convenient for them to destroy the books as opposed to trying to find space to store them. Knowing those companies, most likely they'd be just stuffed into some warehouse to rot after a couple years.