I am a moderator in a forum similar to this one, but smaller. Still, it's the largest german-speaking Diablo3-fansite. I can tell you from my own experience that as a mod, you do not treat everyone the same. It's not about luck, it's about leeway.
If there is some guy who is causing persistent trouble, who has a history of misbehaviour and the notifications to prove it, he is gonna get infracted if he steps out of bounds. That is a given. If there is however someone who missteps and isn't really known for that, maybe he's new or it's his first time in forever to do something stupid, that guy will get a pass most of the time (depending on the severity of his mistake, of course) if the rules of the forum allow it.
History matters in these things, and I am totally sure that the MMOC-moderators do have a tool or two to keep track of previous infractions or just general misbehavior.
http://en.wikipedia.org/wiki/Homestuck
From what I understand, this should cover it quite nicely.
Let's say someone is having a bad day and gives you a ticket for being 1 MPH over the speed limit.
"That's idiotic!" you might say. "No one else gets hit down that hard!"
Well, you could report them for not giving you the same leeway as everyone else due to their state of mind.
But it's still illegal to drive faster than the speed limits.