[FinnKuhn]

Some reasons that the state kinda needs to know where you live (at least in Germany) is for a number of reasons:

- so you can vote in local elections and they can send you your ballots

- taxes, as they depend on where you live (some tax rates can differ and more importantly it decides where your taxes go)

- security, so for example when you have an arrest warrant or have committed a crime, etc. the state knows where to send your fines, etc.

- planning of health services or education services requires the state to know where people actually live