Certain nameless companies thrive on maintaining duopolies by restricting access for competition to expand. This occurs in all fields from telcos…...
In the telecommunications world, legislation was passed that allows a telecommunications company free access to almost any piece of land in the country they choose to put their infrastructure on, in order to give them greater opportunity to compete with the likes of Telstra and NBNco. I know this because I'm one of a few people fighting a telecoms company that have decided our rooftop, beside our pool, would be a good spot to build their "Low Impact facility"; a 3-5m mast with a number of antennae hanging off it.
Morph this into the transport/aviation world and with the right lobbyists you can do almost anything.