Stratfor explains why the term “cartels”, when applied to the drug trade, is a misnomer,
While the trafficking groups in Mexico are commonly called “cartels” (even Stratfor uses the term), they are not really cartels. A cartel is a combination of groups cooperating to control the supply of a commodity. The primary purpose of a cartel is to set the price of a commodity so that buyers cannot negotiate lower prices. The current conflict in Mexico over cocaine and marijuana smuggling routes shows that there are deep rifts between rival groups like the Sinaloa Federation and Los Zetas. There is no sign that they are cooperating with each other to set the price of cocaine or marijuana. Also, since most of the Mexican criminal groups are involved in a diverse array of criminal activities, their interests go beyond drug trafficking. They are perhaps most accurately described as “transnational criminal organizations” (TCOs), the label currently favored by the DEA.
You can read the rest of the report, Meth in Mexico: A Turning Point in the Drug War? on how methamphetamine could pick the winner in the Mexican drug war.