>In real life there is no system in place to prevent people from killing each other on site just to steal their shit.
Well, in some places, there isn't. If the only reason you aren't raping/killing/torturing/ect. is because you're afraid someone else might arrive and fuck you up for it (y'know, "heroes" in this context), then perhaps something is dangerously wrong for you.
I've been in situations in real life where I could have stole something I wanted and almost certainly have gotten away with it. Yet I didn't. Not because it's illegal, but just because it's a bad fucking thing to do. I know how I'd feel if someone stole my shit, so I don't want to do that.
Now if I was starving to death and you had the last can of beans within miles, my "kill you/spare you" scales would start getting seriously unbalanced. But I'd rather not resort to killing someone just to fucking eat.
Truth be told, I really wish DayZ had a big emphasis on killing zombies. I know the awesome DayZ stories stem from human-to-human interaction, but that's also some of the worst moments as well. And it's gotten to a point where the game is just a paranoia simulator.