People forget or don't keep up to date on rules. Some kind of retaking the theoretical parts would at least be nice. For instance the UK has a new highway code (I've heard), and most countries it's quite different to drive now than lets say 20 years ago. For instance the amount of cyclists and the rules around that I feel drivers in Norway have a bad grasp on.

And heck, when I got my license I lived in a remote town, 3 hours away from the nearest street light. Lots of things I got away with not learning, and whatever I memorized for the theoretical test 20 years ago is mostly forgotten. I think many people think they "know" the rules, but really don't