And the same thing can be extended to take your example, don't know why you've put in game theory into the mix, but in general people tend to live better lives where there is law and order rather than live a life under constant threat and having to be the biggest meanest SOB out there to feel safe.
Not to mention that when you live in a society in which your home and self can be raped and pillaged at any moment you tend to invest quite a bit of resources in protecting your own self. While this can still be seen in society today e.g. Police forces, safes, guns etc. It's no where near the amount of resources that would be wasted if you would be living in the wild west.
While it might not be politically correct to think that you live in a society which is more moral and better than others, the truth is that if you live in the west you most likely live in one. And and in fact he luxury of this life style is what allows you to live in that nice little bubble of political correctness.
I personally believe that moral equivalence (or relativism) leads to moral bankruptcy, and sadly too many people have gone under. They promote the equivalence of the moral values of cultures with completely "different" moral values, values that sorry to say in many cases are objectively less "moral" than modern western values. Cultures that if the roles would've been reversed would not only let them speak but would actively silence them.
And while i might agree that everything might be just an opinion as you would said, there just might be some opinions which are better than others. I would like to live in a free and open society, a society that protects it's members and grants them as many rights as possible without hurting the rights of others and without devolving into anarchy. I rather live in a society that does not practice slavery, where women are equals, and no one gives a fuck what is on your plate or who is in your bedroom. And while you might think that a society that stones women for adultery and hangs homosexuals on construction cranes at the local square is just as moral correct as the one mentioned i would disagree. And if you want to quantify that, just quantify the well being of its members, including the ones that would be stoned, hanged, or locked in prison for life for being of or attracted to the wrong sex or simply by promoting other ideas.
And yes there is a good reason why I've not continued to rebuttal on that "stealing from others" example you've given, because It's too simplistic and irrelevant. A society can be morally bankrupt and still practice law and order. And I'm pretty sure that you would not want to live in a society which either allows crime to be committed without consequences nor practices cruel and unusual punishment in some eye for an eye biblical fashion. Because as much as i would think that the guy who broke into my flat and got away with my TV deserves to pay for his crime (and get some help in the process) i don't think that a boy who stole a loaf of bread from the market should get his hand chopped off because the law says so.
Oh and of course this is all my opinion, but i think given the chance we know exactly in which society people would chose to live in.