How can they catch people who have produced unlocked epubs? There are plenty of ways if they have your device at some future date.

I suppose the easiest predictable thing other than having your device seized when you’re entering the country for example or when you get arrested for example is that back doors could be installed on Android or iPhone that look for unapproved media.

The technology is already good enough for that. It’s only a question of implementation.

It’s interesting when people are put to the choice. On the one hand they could purchase a book with DRM that they don’t actually own. On the other hand, they could look for alternative means by which to obtain the book. And the more the publishers f*** with you, the more you might be inclined to never give them a penny.