Actually, it does. It's perfectly legal for a merchant to look across the street (literally or figuratively) to see what his competitor is charging, and choose whether to match the price or beat it. As others in this thread have explained, that's basically what airlines do. Moreover, while the practice may seem frustrating to consumers at times, what law would you propose to restrict it? Should merchants be forced to pick unique prices for everything? If so, is a $0.01 difference enough or do we need a minimum threshold like a $50 difference between identical routings on different airlines?