@jon @DKesserich
I'm surprised that Norway only had the current system for more than 10 years, I'm 47 and my taxes were always prefilled.
Perhaps you mean online for 10 years? That makes more sense, I barely noticed when we switched from paper to online, because that only changed how I didn't have to do anything. And there was a large overlap, with an additional phone based "press 1 to change your personal income" system as well.
In 2008 I needed to make a change, and I had the option of doing it online.
No changes means everything is correct has always been how it worked for me (Denmark).