One of the points that Chelsea Handler's episode made nicely clear was that not everyone who was in the German (or Italian) armies necessarily held strong political beliefs. They were just drafted or conscripted and had little choice in the matter. Also, by the time the war was winding down, many of them were also quite disillusioned with what had happened. Though my branch of German relatives had immigrated to the U.S in 1924, partially because my grandfather, who had served in WWI, was adamant about the fact that his sons would not end up serving a Kaiser and that the conditions of the armistice would almost certainly lead to yet another war, there were more distant relatives that were stuck in positions similar to Chelsea Handler's grandfather's. They weren't particularly thrilled to be soldiers. They simply didn't think they had an option that wouldn't endanger themselves or their families.
As for my grandfather, he did end up sending one son to war--only on the American side. Fortunately for him, the fact that he spoke excellent English, high German, and low German made him very valuable to his battalion's leaders once they got to Austria, as the actual army translator knew only high German (and according to my uncle, not very well). His older brother was given a deferment, because my grandfather couldn't have managed the farm without him (and would have been on the older end of draftable age anyway), and the remaining son was simply too young to be drafted and later got a college/seminary deferment, so he never served in the military at all.