These were “special operations units” that followed the army along the eastern front, systematically killing Jews, communists, intellectuals and enemy combatants – i.e., the resistance, in modern vernacular. All told, they murdered perhaps 500,000 individuals.
Compare this to the 500,000 civilians killed in Iraq and Afghanistan. We give them hardly a thought. They’re collateral damage. They’re enemy combatants in civilian clothes. The resistance!
Stalin’s purge machine operated much the same way, indiscriminately killing Stalin’s enemies with the most convenient tool available – bullets, starvation, or just the extreme cold of Russia’s winters. 65 million is the death toll, over 100 times more than the einsatzgruppen, and you’ll be hard pressed to find anything about it in any modern histories.
Death by government is covered up by; well, government.