I don't think they would draw a line at anything. What is the motivation for being a footsoldier? Is Mexico that poverty stricken? Living with knowing you could be captured and decapitated or something.
Many of the people being killed are not cartel members per say but criminals or normal people that are hired by the cartels and also again take the drug war homicides or victims with a bath of salt. The reason some decide to kill is to become more recognized and get higher or integrate more into the structure resulting in getting paid. But it's not always it's not uncommon when the cartels use these people as cannon fodder or point of the spear.
