I'm kinda creative with these suggestions

I would like to suggest a whole new way in calculating passenger numbers, inspired by another suggestion.
Instead of having fixed numbers for the airports, we could make fixed numbers for the cities/areas served by the airport. Then the airport passenger numbers are calculated by flights, and the loadfactor is calculated by the city's population.
E.g., big cities in Africa have small airports, and small cities in US/Europe have big airports. This suggestion will bring more balance into the system, and you can see if the passenger number in the airport changes when you make routes to the airport.
And when runway lengths are implemented, you can rent a gate at a small airport for a small fee, and fly into a big city. But when you want to upgrade your planes to earn more money, you will have to switch to a bigger airport.
If possible, a negative factor to the loadfactor would be different parametres, e.g. distance to the city, size of airport, and make the bigger and more expensive airports more attracting.
This could also make possible a fixed number of gates for all airports (e.g. 50 or 75), and then the big cities would have more airports, with more gates per city in total.
It can be discussed what the "catchment area" of an airport is, but some airports near, e.g., Paris are so small, that only very small aircraft can land there (runway lengths).
If this suggestion comes into consideration, I will gladly research the city population numbers needed.