Oh, you're quite right, there's a contradiction there. I can think of ways to resolve it, though, e.g. a swap club that checks the actual library holdings of its members in some way. There's a service like this for the blind:
http://www.bookshare.org.
I think you're right, there's a cultural difference here. I've bought additional copies of books in the past if I've lost them or they've gotten damaged, and I don't really mind doing so, but I'd rather be able to keep a backup and retrieve it, and in my mind, that's probably better for the environment as well, which is also important. I'm not saying this to try to get you to agree with me, only explaining my point of view. Perhaps we could agree to disagree on this one.