There is a user in S4E that owns 3 airlines in a world where only one is allowed. They take over the alliances and make theirs the one with the best destinations.
How do I know there are by the same person?
There usernames are all "jgg+[plane number]" Like jgg707300.
They both use the same planes, (Antonov An-28, MD-81, MD-88)
They all have no airline description.
And they are all in the alliance OneWorld, which they cheat their way to making it the biggest alliance.
I know the game will probably never remove them, but just watch out if the airline JATAM is in your world.