That conflates two very different things:

* A conventional military war, on a battlefield: Neither Saddam Hussein's military nor the cartels nor the Taliban would last long against the US.

* An unconventional insurgency: The Iraqis quickly turned to this approach and it worked very well for them, as it did for the Taliban. The Taliban won, and the Iraqi insurgency almost drove the US out of Iraq and was eventually co-opted.

The cartels of course would choose the latter. They, the Taliban, etc. are not suicidal.