It's less about the government and more about the populace. A great many of the people of Germany were complicit in the Holocaust. Those that didn't work in the camps (or even know what happened there) were still reporting their neighbors and having their children join the Hitler youth. Much like the US South where black folks continued to be surrounded by racists that (for over a century) would lynch a formerly enslaved people with no repercussions, the Jews would be living amongst their former oppressors.