I think the specificity of the Jews, Gypsies and others sub/non human by the Nazi is the very well planned operation. The death toll in the Boers concentration camps built by the British is due to the neglect of hygiene principles. But can I remind here what the level in science was at this period? Pasteur, anyone?
The camps built by Nazis were designed to kill. The huge death toll in the Gulags is due to the harsh conditions, and mistreatments and all others factors we know, but the purpose was not to kill every body.
Treblinka was. And thousands were. The length of the train, the numbers of people transported were calculated to insure that when the locomotive had done all the refuelling in sand, coal and water, and turn in the right direction, all the wagons would have been clean and the deportees dead. All the system was not done to submit the occupied populations. This was after all the German philosophers. It was done by one of the most educated and cultural nation in the world. The barbarians from inside, the inner Tatars… And no offence meant to the Tatars. To compare a Nazi to a cockroach is an insult to the cockroach.
Yes, this genocide was made possible by the technology. And that is why I think that the figures are in fact underestimated.
What is surprising and amazing is the fact that some still don’t grasp the fact that Hitler and consort killed their own people, their slaughtered the men and the families of the men who were fighting with them in 1914-1918 in the trenches… And this madness spread too easily to the rest of European mostly Christian. The French, the Dutch, all the occupied countries authorities collaborated. Same of Hitler’s allies, they all ended to do it.

Pz, by the way, there are no evidence that the US President knew about Pearl Harbour. More, even if he would, what to do? Tell the Japaneese to pull the plugg off? We are agin the same kind of ... than for the Twin Towers...