A long time ago, before the European Union, I made a business trip to Burghausen in Germany on the Austrian border. I stayed in a hotel on the Austrian side on the other side of the river.
If I used the foot bridge over the river, my passport was scrutinized on both sides. If I used the car and took a detour over the motorway bridge nobody cared.
This is typical for the way institutions like Royal and not so royal mail systems, border police and customs offices work.
Once when I was getting off the ferry from Sweden to Germany there was a special razzia for contraband and every car was searched except mine. Why? because I declared an expensive instrument that I wanted to get back with no fuzz. I spent a little time in the customs office and was then waved straight on without any search.
This is why those of us who send banknotes get away with it. No Postal system wants you to send money in letters. They want to charge you extra and threat us with various regulations. I doubt that any Norwegian has been brought to court for sending undeclared money but I might be wrong.
Göte