They're just the ones who got caught. A lot of markets have only 2 or 3 major players. With so few players they could cooperate to raise prices without doing an

They're just the ones who got caught. A lot of markets have only 2 or 3 major players. With so few players they could cooperate to raise prices without doing anything more than observe what each other are doing and responding accordingly. Price being the only means of communication or coordinating between the players.