Earlier quoted context omitted.
In Germany every person eligible to vote just gets a letter telling you the day of the vote and your voting station (and a list of stuff being voted on, local elections usually coincide with more important ones). At voting day (a Sunday) you go to your polling station with that letter and photo id and after five minutes you have cast your vote and are on your way. It's dead simple. But it hinges on the state having a…
I mean, that's largely what voter registration is - a database of every citizen's address. The problem comes in when those addresses change. There's no requirement to inform your old state you left, so millions of inactive voters are left in the database. Generally there's a requirement to register in the new state (drivers license) within 30 days which is often missed, or not required for temporary moves like colleg…
In Germany when you arrive somewhere we know that you are coming from somewhere. So when you register at your new address that usually involves your new city hall informing your old one that you moved.
I guess that doesn't really work if registration isn't universal (in Germany we track you place of residence basically from birth, it's used not just for voting but also for determining where your taxes go, for government communication, to make sure nobody skips out on bills by moving, etc).