When I took history in High School, we were shown films of Germans being shown video of the Nazi death camps and the enormous number of Jews killed. Piles of reading glasses. Gold melted down from teeth fillings, mountains of shoes and so on.
Many Germans claimed to have no idea this was going on.
Hitler was tricky. He convinced his people that these Jewish interlopers were taking German jobs and getting government help that should have gone to Germans. We know that for the ignorant, these tactics work well.
So the Jews were rounded up and sent to camps in remote areas. The press wasn't allowed in. Germans who weren't "dedicated soldiers" of Hitler weren't allow in. In this way, atrocities were kept secret. And those loyal to Hitler defended him. Many, not even knowing what they were defending. Of course, some were evil and even knowing what was going on, didn't care or even approved.
Camps in remote areas?
Dirt walls being built up so no one outside could take pictures?
Detainee's being secretly moved?
Elected public officials being refused entry?
Video and pictures provided by the Government?
Where else have we seen such tactics?
You are out of touch with reality. Whatever happened in those camps, their official purpose was "concentration". The "Final Solution" consisted of the deportation of the Jews to Madagascar.
Also, the Jews were not immigrants, respectively, they were immigrants centuries ago, when they were invited by some King or something to help stimulating the economy. Problems with Jews were entirely about their position on the financial market because it is was not ruly for a Christian to demand interest. The Jewish bound of German soldiers is an example that Jews felt quite German before Hitler.
Second, you talk about a brutal, oppressive regime and on the other hand you demand the Germans to stand up. If people had known about killings in the camps, this would not have constituted a good reason to stand up unless you wanted to end up there too. The Weiße Rose people who tried to alert the people with fliers were beheaded in the end.
All the "evil nazi citizens" thought they were right.