As I understand it, the overhead robotic camera was instituted originally by NBC for their Sunday Night Football broadcasts. Special permission has to be granted by the NFL, as well as the teams playing the game in order for them to be installed for each game. The other networks have "borrowed" the idea, but because it is such an expensive proposition, you will find it used only on "national" telecasts, not "regional" games. Sunday Night Football, Monday Night Football, Thanksgiving Day games and playoff games all fall into that "nationally televised" umbrella. Those are the games that get the biggest ratings and the networks make more money on those games.