In addition to what has been said already, I would imagine that the more highly educated and politically engaged you are the more likely you are to care enough to update your voter registration.
For example, who do you think is more likely to care enough to update their voter registration, Harley Rouda or these people?
https://youtu.be/IhporHhKbJA
Pretty much everything you said is on-point, and this is kind of off-topic, but your post is what led me to research more about Harley Rouda and find out just now he went to the University of Kentucky. I guess that's kind of an odd coincidence considering what we're talking about here.