NBA

What? Sports referees are biased and are screwing my team? It is a story that started as soon as the first game with a referee was played. Refs are human and make bad calls. They will sometimes make a mistake and overcorrect or make a makeup call. Also, even with perfect refereeing, if you slice the stats enough, you will find bias in random noise.

As for the NBA, there are known biases: if a superstar and bench warmer make contact on a play, the refs will always favor the star. Bigger players are allowed to bang in the paint while smaller players are protected. Refs will only call a blatant charge and never if there is a defense foul on the play. As long as I can remember (20 years), if a player or coach whined about refereeing after the game, they would automatically get a fine but coaches would still do it so that refs favor their team's next game for fear of providing evidence to the story.

There is always a story that the league is pushing the popular team. Before the Lakers it was the Warriors who the refs favored (it was ~~infuriating~~ fun to count how many moving screens Draymond could get away with).