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?
Doubt it. Because then it becomes a question at resolution, where too high results in countries with infinite area, since ever slope, ditch, and grain of sand has to be accounted for.