The real reason?
Airports have to pay to have something on. If they were to get regular cable, the fees would be huge.
By putting up a satellite dish they can access a specific version of CNN dedicated to airports. While it looks like your normal feed, it is designed specifically for the airports.
The airports get something to put up on their TV screens, CNN gets very targeted ad revenues. And travelers get something other than a blank screen.
So, all in all, it comes down to money. And the folks at CNN get to the market first with a specific product at a cheap price.
Just like everything else in the world.
It has very little to do with politics. And yes, it would be suicide NOT to have CNN on at Hartsfield.
And those CNNs in the medical facilities are dedicated CNN feeds that focus on health issues.
Very rarely will you see “Cable TV” CNN on any of those TVS.
The reason they do not offer channel choices in the airport is that for every channel there is a very dedicated fan base.
Who would be responsible for setting the channel? It would be a mad house. People would die. Cats and Dogs, fighting in the streets....
Seriously...you would NOT want that job after one day.