In the US, we used to have NFL blackout games. If the football game wasn't soldout, the NFL wouldn't broadcast it on TV. So local businesses or the wealthy would buy the unsold tickets so that us poor peasants could get to see the game on TV. I don't know any games that were actually blacked out since football is so popular and most games get soldout before the season starts. But once in a while news of the potential of a black out game spreads and the unsold tickets get bought up and the game is televised.