People don't understand and therefore attack
Those that attack this movie seem to not full understand what people,
given seemingly absolute power over a group of "inmates" are really
capable of. Any of the things depicted did not surprise me in the
slightest, but I've had a chance to seem human nature in some of its
purest form. If you think most people wouldn't do what those guards
did, you are lying to yourself.
Otherwise, how can you explain why the world is as *beep* up as it is?
Because most humans are capable of atrocities when given the chance.