Same Day Registration (SDR) gives voters the opportunity to register to vote or update their registration when voting early and on Election Day. Voter turnout in states with SDR was seven points higher than non-SDR states.
Somehow I missed this for the Quasi-Mandatory Voting post. If you achieve automatic registration, then you don’t need SDR because it ought to already be handled. But, maybe a voter got the license on the day prior to the election and the automatic process takes up to a week, so SDR would help someone vote.