I suppose it's cultural differences. There's a staunchly individualistic attitude in the US and the idea of a central government tracking its citizens is very unpopular. I get it, too. If you take a look at the "Anmeldung" process in Germany, where the government has a list of everyone and their race/religion/nationality, along with exactly where they live/which building/which floor/which side of the building, you can see how such a system could be dangerous if Germany were to ever shift from the liberal democracy it is today.