For example on wikipedia for Switzerland it says the country has an area of 41,285 km². Does this take into account that a lot of that area is actually angled at a steep inclination, thus the actual surface area is in effect larger than what you would expect when looking onto a map in satellite view?
I can’t remember if it was Matt Parker or Tom Scott who did a thing about this on youtube, and I think the answer was no, they just use whatever method is easiest to get these numbers, and they’re not even using a consistent methodology from one country to the next.
It was by Matt Parker. Here it is: https://youtu.be/PtKhbbcc1Rc
or watch it on piped.video if you prefer: https://piped.video/PtKhbbcc1Rc