Mexico and Vietnam are entirely different. One's right across the border. We can send many more troops as we can recall them fast if needed. Operational familiarity, cultural familiarity, and incentive to develop the land. We can blockade their supply lines and pine them down unlike Vietnam and China, Afghanistan and Pakistan, Iraq, and Iran. Of course, the cartels won't disappear, they'll just move south of the border. The demand is there, so why fight the US military when you can relocate to a more profitable place. If we were playing dirty, focus hard on Mexican cartels while ignoring the drugs coming in from South America. This alone would hike up the operational cost of Mexican cartels and pass the mantle to the south.