One thing that OMC bikers like second to drugs and booze is fighting, mainly each other. It's a past-time, sport and calling to them all in one; most of them tend to like it more than making money on illegal activities. Even if the nation-wide bosses of the Big Four got together and tried to enforce some kind of Commission-type treaty, they couldn't hold it together if they tried. There's just too much drugs and to many loose cannons out there in the OMC scene to make it work.

Hell, their guys would whack the bosses for trying to enforce it and ruining the "fun".