No, they weren't the norm. Not until Axis forces demonstrated that it was top-down policy.
Nazi Germany had spent a decade of propaganda, bringing up its youth to believe that they were the Master Race, that their opponents were subhuman or evil, and that it was necessary to "clean" the world to remove the threat. They made a specialty of the murder of civilians in Eastern Europe, and was none too unhappy about translating that behaviour to Western Europe. They did this to PoWs and civilians from the very start of the war (Le Paradis, Wormhoudt), and before (see: Guernica), right to the very end (death marches of PWs). Unsurprisingly, the Eastern Front quickly became "no quarter asked, nor none given".
What's depressing is the number of alt-right types in the USA who now believe that the Germans did nothing wrong, they were forced into a war by the nasty aggressive British and French, and look! The Soviets were beastly! CoMMIe sOciaLIST AnTIfA BlM!!! Or is it the other way around? "I rather admire black uniforms and swastikas, and enjoy some casual racism, but I don't want to think I'm a bad person, so the Nazis must have been right, so I'd better make up some reasons that I can contradict all the evidence and history books"?
That's the informed opinion of a US teenager who has never served a day in uniform?