Significantly, the Germans of Weimar, after WWII, almost universally professed total ignorance of what was happening in the concentration camps of Germany and Eastern Europe. But....Buchenwald is approximately six miles from Weimar, and in the last two years of the war, as the work forces were rapidly depleted to replenish the military losses, prisoners in shackles were brought to the local factories, standing side-by-side at assembly lines with civilian workers. How those workers could ever claim ignorance is known only to them now, but yes, of course they knew. They all knew.

But as to why it was tolerated, once an extremist group in any country takes control of the military, the civilian sector is rapidly subdued, and understands that the only two responses to authoritarian behavior are tolerance or extermination. That is an extremely powerful motivation, be it in Nazi Germany, Egypt, Iran, China, Russia, or Uganda.