Political Memes

That's not entirely true. Most Germans absolutely knew something was up with the Jews, and others, and pretended not to. Out in the country, where the Concentration Camps were, towns and villages knew what was happening, and could smell the crematoriums. Many of the workers at the camps lived in the villages, and businesses in the village did business with the camps. Many had to have seen, or at least heard about the conditions.

In the cities, it was pretty obvious that Jews were disappearing, usually in harsh and violent round-ups in which any resistance was met with instant lethal force. Neighbors, employers, local business people, etc. certainly noticed that the local Jews, gays, activists, religious figures, etc. were disappearing. Of course, EVERYBODY had been exposed to years of the most ferocious anti-Semitic rhetoric, far worse than what we hear today about undocumented people in America, which included permanently eliminating Jews from the entire planet, so they could pretty easily guess where those people had gone, never to be heard from again. As bad as MAGAs are, we haven't heard them openly calling for an official policy of extermination...yet. I truly believe it is coming, though.

Of course, after the war, nobody was going to admit they knew something was going on, and did nothing about it. Better to just act ignorant. Better to be thought to be stupid, than to be thought to be evil.