Oh yeah, we are very different then Germans. We have different values and political system. We have overall much lower levels of violence. We could become like Germans, but overall, we are not nearly there. Hitler did not became leader randomly and his ideas and opinions were not formed randomly. His competitors for power were different then him.
Among other things, the social darwinism and race believes of Nazi were formed by bad contemporary science (and misuse of it). They believed themselves to be rational and the right kind of man. Guess someone needed to hair split those ideas more loudly long before.
The academic hair splitting matters. The truth matters and the truth here is that this particular experiment did not shown what Zimbardo claimed to show.
In practical politial consequences of time, this experiment was used as argument that you can't possibly make prison less abusive. It did not shown that at all, it shown only that it is possible to make it abusive if you want to. Difference matters, because if you stop trying, well then conditions won't improve.