I would say this is correct. But if they want to have someone taken out or path cleared for their organizations, they will do it to make it look like it doesn't involve them. Going into a McAllen neighborhood like they do in Reynosa won't fly here for obvious reasons. The way they do it is by bribery, buying stash houses in affluent areas, and other stealth like tactics to accomplish their goals.
And really I think the bulk of the cartel stuff on the other side of the river that makes the news is happening in Reynosa, Juarez, and Nuevo Laredo. I feel "safe" going over to Nuevo Progresso or Las Flores as we natives still call it as I did decades ago. Always kept my money in my front pocket then and do it now. You don't hear much of stuff going on in Matamoros, Acuna, or Piedres Negras other than the on going immigration non sense. The cartels are involved deeply in all of that and certainly have their base of operations in those towns, but the shooting wars are just not as apparent as in the other above noted border towns.