I can go with this. Germans were by no means homogenized, but they were more than the Italian states. Divisions in Germany today tend to be the prosperous West vs. the still re-emerging East. In Italy, there's outright racism directed toward southerners. Italy is more like the former Yugoslavia.

Plus, while both Italy and Germany were ruled by the Holy Roman Empire, the transfer to a more Austria-based kingdom would have been less severe to the Germans than the Italians, who would have felt driven to unite in order to remove an invading alien culture as opposed to Germans just wanting statehood. Maybe. I wasn't actually there.