The Dunne red card is a case in point. Earlier in the game, he forearm smashed a Livi player - a clear sending off and Collum missed it. Somebody obviously has a word in his ear and he just waited for the next chance to get Dunne. He was so keen, he made an arse of that anaw.
Nobody really believed Macey would walk for elbowing Lamie, but you know exactly what would've happened if the roles had been reversed. And with Roberts, even Collum must've thought twice about dismissing two players from the same team in the first 6 minutes.
VAR will sort out offsides, cos they just draw their lines and that's that, but for red cards, penalties, hand balls etc, it'll still come down to a human making a decision. How many ludicrous rulings have we seen in the English Premiership?