The vast, vast majority of violence that happened at my school (and we had a fair amount) was between unpopular, non-nerdy kids with homelife problems.
Physical violence was mostly between the bullies/"bad kids".
While I was nerdy, these things happened more because of differences of ethnicity than anything else.
When I left NYC I met someone who claimed that he had "never been punched" and I thought that was the craziest statement I had ever heard.
I am near two high schools in downtown Oakland and I have seen only 1 fight in the past 2 years. I think that today's kids are much less prone to violence even in the rougher neighborhoods and adults are much more likely to intervene.
People draw the line at different points. Some might consider the shoving that happened frequently to me one year something far worse than what I considered it to be (frustrating and annoying, but not causing me any anxiety for fear that it'd happen again, I knew it'd happen again, but I didn't have panic attacks about it).
Same in India as well.
Also, no, it didn't matter who started the fight. If you were involved then you were equal and disciplined the same. It's ridiculously backwards
The teachers naturally will "like" the talented social sociopath, so they forgive and don't punish their transgressions against the weak.