You've got it wrong in the last sentence. We do expect the same societal standards from criminals as we do from police and other upstanding members of society (ie: don't beat people up). Criminals choose to disregard these, which is what makes them criminals.
That to me is the problem. If a passer-by disregards the law, that makes them a criminal. But also, if a police officer disregards the law, that makes them a criminal. The first part usually works. It's the second part that people (especially people in power) keep having such trouble with.
PS: I know "obey the law" isn't that cut-and-dried: unjust laws, civil disobedience, etc. But I'm speaking generally.