I've often wondered if DRM advocates realize this. It's hard to see why they couldn't since it is their business to know. It's hard to see how they couldn't since even people like ourselves know, and it isn't our business to know.

It leaves me wondering if DRM is actually meant to inconvenience paying customers. People who lend books out, give books away, or resell books are cutting into sales from the perspective of the business. If you make the assumption that book buyers are law-abiding, then it may be possible to badger them into the one sale-one reader mentality. Pirates are a different issue. DRM may not hinder them, but it doesn't help them either. So if you can extract more sales out of law abiding readers, and are doing little to aide the cause of pirates, why wouldn't you implement DRM?

Of course, the people making these decisions may be so thoroughly hidden away in their silos that they think that DRM is effective in preventing piracy.