In the NFL, teams share revenue from national television contracts and to sell local tickets, if a team has not sold at least to a specific threshold, the game is blacked out locally. If enough people are attending, the game is shown to fans in the region
That appeals to 'hometown' fans. One satellite network shows all games to its package subscribers but otherwise fans are only going to see their local team. If they don't have one, they see something nearby. It is a rule and there is no choice.
In the modern mobile population, that may not be a wise strategy. Fans no longer live within an hour of where they grew up and a new paper finds that choosing to broadcast the local team isn't always the smartest ratings decision. Writing in