Mikejw, my family's friends in post-WW2 Germany, when asked why they didn't ask about missing neighbors, they said, people who asked questions disappeared.
When asked why a German had not wondered what was happening in Dachau, he lived only 5 miles away, and could smell the smoke and the smell of burning bodies: He said "Although Karl had grown up in Munich, he had never been to the
camp.
"What did you know about it during the war?" I asked him.
"Now you can get on a subway, but then it was very far away," he
answered. "It was on the other side of the woods. We heard that
something was going on there. But we didn't know what it was. We knew
that it wasn't good. But we didn't ask questions then. It was too
dangerous. We knew what happened to people who asked questions. "