Flight controllers in Mission Control in Houston use NASA Television to watch what the astronauts are doing on-orbit. Similarly, engineers study NASA footage to assure that the Space Shuttle launches and landing went as expected. Researchers on the ground also use NASA Television to see how their experiments are performing on-orbit. Secondly, NASA is not a broadcaster and, furthermore, is not allowed to compete with private broadcasters. The Federal Communications Commission has strict rules about who is able to provide broadcast television.
Television is one of the most cost effective ways to distribute such information.
Most local cable stations are able to downlink NASA Television to add to their line up if they wish to do so. Similarly, most direct broadcast satellite providers are also able to access NASA Television to offer to their subscribers. Since NASA TV is not a commercial production intended for the general audience, NASA does not lobby cable or satellite TV providers to carry the signal. Choosing whether to do so is entirely up to the provider. The live satellite interviews are a service that NASA Television provides to local and national news organizations so that people all over the United States can learn more about aeronautics and space research and programs.