It's one law that every single country has on the books and no one ever enforces - observe how it has no provision for anything that you actually own, if you go out of EU with your MacBook Pro and come back you should technically be declaring it at customs as an item over the allowance value. You should be declaring your phone and your watch if it's an expensive one too. Literally no one does this, and if you do try declaring those items you will be just waived through for wasting the guard's time.