Just logically, if you think of the scale that the Cartels are working in, there is a missing link in the narrative here. Mexican cartels are completely intertwined with the Mexican government. This is well known in Mexico, as is well known that the US is the greatest consumer of these substances.

Organizations at this scale have infrastructure that rivals a multi-national corporations. But in our collective imaginary, we never talk about who receives it in the US. The story goes cartels -> ??? -> small to medium street dealers. At the scale of this problem, we are simply dealing with a level of sophistication that requires connections in VERY high places of the US government.