American Airlines is retiring its Phoenix to Monterrey nonstop on December 1. No other carrier flies that pair, which means the only direct air link between Arizona and Mexico's industrial capital disappears with it. The airline's reasoning is straightforward. The route was running near a 60 percent load factor against an industry breakeven closer to 80 percent. As reported by TheStreet, low demand drove the decision. I would read it differently. Leisure routes out of Sky Har