Dead people means soldiers who should be fighting are cleaning em up. Dead people can't work as slave labor, soldiers keep crappy records. Jews are more easily identified by bureaucrats than soldiers, and once a bureaucrat has em, they're going to want to get all the paperwork done (there's tonnes of it, literally).The reasons are plentiful, the records show it being done, the eyewitnesses corroborate the records. The facts are there, the facts have been verified.

They shot plenty of people, but it's better to shoot at the ones that shoot back, that's an efficient use of bullets.