@mattwilcox we have automatic voter registration in Germany for citizens. However, the government or to be more precise the local municipality needs to know where they can send the voter info before the election and - if you do want to vote via mail - an address to send you the ballot. To be able to do this, you have to register with the municipality once you move there. This address is also used for all other affairs with the state, like taxes, trash collection, etc.