And fwiw, let's say crowds are the cause of this. Your team, over the course of the game, has given away some legit penalties. You're behind in the count. The ref starts to think your team is taking the mickey a bit and you fall behind a few more. The fans of that team, and it could be home or away at this point, are really starting to kick off and get on his back about it...
If the crowd is the cause is that not then the perfect recipe for a referee, again unwittingly, somewhat evening things up?
I don't think it has to be concious choice on the part of the ref' at all for this to happen.