I'm sure if you did a poll in Germany you'd find a non-zero percentage of people who'd answer something similar RE the Nazi flag, with the right wording. Nothing like 40%; that particular variety of lost-cause-ism isn't as common as the confederate stuff in the US, but, there are certainly people who would claim that it was something more benign than it is generally perceived.

That's why it's illegal in Germany in the first place; if there was universal acceptance that it was an obscenity there wouldn't be much purpose in banning it.

Another issue, of course, is that teaching about the US civil war, and general cultural treatment of it, has been, and in some cases still is, far more dishonest than teaching about World War 2 in Germany. Note that in this thread there are people questioning whether it was about slavery. The initiators on the confederate side would not have questioned that, they could hardly have been more clear that it was. There's a huge amount of mainstream cultural baggage glorifying the confederacy and important confederate figures in a way that there isn't about the Nazis (with the possible exception of some rather creepy Rommel apologia that shows up sometime).