This is probably one of those situations where he thought he got away with something, and $100 is $100. However two years later after the fines and jail time, it’s probably an overwhelming amount, he has no choice but to double down on stupidity.
But to give a more serious answer, it highly depends on locality, and I didn’t see that.
Where I live, a simple registration renewal is $60. However you need to pay any back fees and you may need to pay fees for new plates. But you also need to get caught up on paying excise taxes to your town and get clearance from them to proceed. And you also need to get caught up on all traffic fines from all jurisdictions, and get from all of them a clearance to proceed. And you need to have current car insurance at least the minimum mandated by state and they need to update the registry. And you need a valid ID, such as a drivers license, which also has snowballing prerequisites. It can quickly become a real pain in the ass, and add up to a lot of money, even for an older car without much value. You know he’s been applying the same stupidity to all the prerequisites mandated by whereever he lives, and has made it as difficult as possible for himself