Designing a surveillance regime whose first line of defense is "Come on, we're all good people, what could go wrong?" is either naive or cynical on its face.
The most important thing to understand about the "stupid or evil" question is that in terms of results, it doesn't matter, so it should stop mattering to us. Just assume evil. If you assume stupid, and they turn out to be evil, you'll be the worse off for it. If you assume evil and they turn out to be just stupid...who cares about stupid assholes?