I get it for a smart meter, you don't want to mix up numbers and provide wrong readings. And they could be read manually and entered into a system, even if they

I get it for a smart meter, you don't want to mix up numbers and provide wrong readings. And they could be read manually and entered into a system, even if they're "smart". But for books, the worst that can happen is that you get the wrong book. Maybe back in the days when people ordered books via phone it was good to have a checksum, but even then the seller would probably read back the name of the book. So I don't really see how it's necessary here.