Because CNN has bought the airport TV news franchise and installed the TV’s in the terminal buildings . . . they own it, basically. Airports sold it to them, believing that they were getting a real news channel, not a propaganda outlet.
Of course, remember too that most U.S. airports are government agencies, too, so there’s some affinity there.
Half of all of MSDNC’s viewers were of the “Schadenfreude” variety.
They’re following Err America down the drain.