It's remarkable that Sir Alex Ferguson was so successful at Manchester United considering the referees are always against the Red Devils. It's one of the many hardships of the club. Just ask David Moyes.
Moyes: "We are having to play the opposition & the officials at this moment..maybe I've got to understand that's what happens at Man United"— Rob Harris (@RobHarris) January 7, 2014
Read that quote again.
One more time.
Done laughing yet? No.
Read it again.
Other possibility: referees have always favored aggressive teams. You can't get a penalty when you're not running forward and you're more liable to give away a penalty when you're lunging from your heels. That's the nature of football. It is also a trait that most good teams have, so Moyes might want to consider that regardless of the referees.
One more possibility: Moyes' is right and the referees are acting on behalf of the Illuminati, who see Manchester United as a threat.