I think what happened in Nazi Germany could have happened everywhere at any time (including the future). People tend to close their eyes when something bad happens and it doesn’t concern themselves. That’s human’s nature. That’s no excuse, not at all, but before judging the people for not doing anything you should ask yourself if you would have stood up in this situation. If you’re answering this question within a minute with “yes” you’re not thinking seriously and you lie to yourself.