My theory in why Los Zetas hasn't sufferred internal splinters/friction like other cartels mainly the Sinaloa Federation. Though over the years of Felipe Calderon over 80 captains, local bosses, regional commanders(bosses) and leaders among them both of the Los Zetas leaders, Miguel Angel Trevino and Heriberto Lazcano, both go respectably leaders of the Los Zetas network. Unlike other cartels were many of the mid level and upper members of the structure are involved in drug trafficking and distribution. They have the resources to become independent when the government deals significant blows to the network that it causes some players to lose contacts with their parent organization. This has been in a lot of the splinter groups that come out of the Sinaloa Federation but internal conflicts also do account to the splinters. The Los Zetas operate as a brand per say, when they go into a new town they ask or force the local thugs from that area to use their brand name to sell drugs locally, extort, kidnap for ransom, steal cars and other activities in exchange for profits or royalties to the command and control structure which are the regional commanders(bosses) and the leadership. The reason why these local franchises can't afford to become independent from the regional bosses and leadership is because they simply can not afford to become independent for many reasons, mainly because they don't have the resources to combat the regional bosses and the leader. All of the low risk high revenue rackets like human smuggling(which is a 7 billion year business), oil theft, and drug trafficking/distribution is monopolized by the regional commanders and especially the leader. Miguel Trevino had created a pretty efficient business and structure model that guarantees loyalty by kickbacks, and complete control of the organization by monopolizing the high profits rackets. He created all of this by snitching and killing all of the regional commanders he deemed a threat to his complete control of the organization and replaced them with people he trusted or were loyal to him. He was also pretty smart with the drug trafficking aspect of the business's. Instead of using members of Los Zetas to traffick drugs he was using private people to take care of the drug trafficking business to not get indictments in the U.S.A.