I think the interesting question here is to what extent are the personnel responsible for building this comm infrastructure kidnapped/enslaved/coerced versus being there mostly voluntarily. There's some merit to the argument that it's much riskier and probably more expensive for the cartels to kidnap and hold these people than to pay them enough to work voluntarily. The main argument against that is how many people have disappeared with no contact with their families, and that the families aren't getting any money. But then, we don't know where these people are, what they're doing, and what degree, if any, of coercion is being applied.

The wild card is the Governments' unwillingness to even acknowledge the problem. That suggests that it embarrasses them. What's more embarrassing to the government, though? That the cartels might be powerful enough to kidnap people at will all over their country? Doesn't sound particularly newsworthy or worthy of suppression, considering what else is going on there. How about the extent to which upper-middle class educated people are willingly working with the cartels to build high-end infrastructure? I could see that being very embarrassing indeed. It makes it seem like the cartels are inching closer to being the legitimate government of major parts of the country. That sounds much more like something worth denying and suppressing. I have no idea if there's any truth to it, but the motives seem to line up in that direction.