To be fair there are plenty of countries that are very strict about modifications. Australia doesn’t allow engine modifications as far as I understand it, even though lots of people do modify their cars.
Agreed, it is a pretty ridiculous rule regards changing the wheels, but in reality nobody really cares IME. My car is running wheels 2” bigger than standard for the last 10 years, never even had a comment after several inspections. It’s not a legal matter, they might just make you put it back to standard.