Just to be pedantic, no one is actually required to accept currency to settle a private debt. Not that it changes the thrust of your argument a whole lot, but private entities are not forbidden from rejecting US dollars (or pennies).
Actually, El Paso, TX has been rated the safest or one of the safest large cities in the United States for several years. (http://www.kvia.com/news/25870470/detail.html) I don't know what conclusion you want to draw against that, but Ciudad Juarez, right across the border which is supposed to be so permeable to drug violence, is once of the most dangerous cities in the world, with 3000+ murders last year. Kind of blows a hole in the theory.
Actually, TFA mentions that the cost of shipping empty containers is very close to the cost of shipping laden ones.
Before you go lumping an entire ideology in with one guy's stupid opinion piece, let me ask you this: Who the fuck is Bill Sardi?