If you break a book at the library, you usually have to pay for its replacement.
Sure there is some normal wear and tear that isnt "breaking the book", but if you browse through your library you will find lots of books that were purchased 20-40 years ago that are still in good shape. I don't really think normal wear and tear is very significant.
I mean, from where i'm sitting the logic is "how can we extract as much revenue as possible", with the wear and tear argument being post hoc justification.
Sure there is some normal wear and tear that isnt "breaking the book", but if you browse through your library you will find lots of books that were purchased 20-40 years ago that are still in good shape. I don't really think normal wear and tear is very significant.