It is the classic scenario of confusing the map with the territory.

In the map everything is clear. It is clear what a "plane" is what "airports" are and what their relationship is. And transferring that into a computer program is straight forward.

In the territory everything is fuzzy. None of the definitions are without edge cases and the expected relationships are often violated in surprising ways.

Aviation isn't unique here, every system suffers from the distinction between its actual function and the abstract description of that system.