mxyzptlk, you can talk about violent culture, but the Australian contact codes have a lower level of crowd violence then the A-League and significantly lower than European Football. Why is that?
No idea -- it may be a soccer thing. An acquaintance of mine did his master's thesis on soccer violence, which always seems to be a proxy for political violence. Whether it's ethnic differences, religious differences, or historical differences, the places where hooliganism seems to erupt seems to come from those populations having unresolved issues with each other, not having good avenues in daily social life to deal with them, and using football as a proxy to work them out. Then group think comes into play. (If you're into that sort of thing, there's a psychiatrist from Cyprus who specializes in group psychology and political tension, Vamik Volkan -- he's excellent for getting a handle on where something like crowd violence emerges from and why it occurs. He's been brought in to help with Northern Ireland negotiations, Greek-Turkish talks on Cyprus, Palestinian-Israeli negotiations, Croatia, Georgia, South Ossetia, that sort of thing.)
The other side is (like I mentioned above) that maybe the contact code crowds vicariously enjoy violence at a distance. They want to see it from a safe place, but aren't as willing to get up close to it -- whether that be ringside, where it's more real, or amongst themselves.
The difference -- at least in how I'm looking at it -- is in the media presentations. You don't see the EPL promoting their game by showing fights, not least because there's enough trouble with hooliganism in the stands. But as I understand it, rugby league's advertising packages used to feature fights on the field.
From an outsider's perspective, when I see someone take a whack at someone else on a field, I think that's not part of the game, knock it off and get back to it -- channel that aggression into winning something instead of breaking your knuckle. But what I hear from NRL commentators is stuff like he's just having a good hard crack and showing he's up for the game. Which makes me think "wrong game." Maybe they should wear mma gloves.
And just to be clear, I'm in no way saying the U.S. is any better in this regard. We may not have as much violence in our pro sports (and outside of hockey our media would only frown upon it), but we now have spree killings about every fortnight. We can be a horribly violent tribe, and we don't express it very constructively.