Competition in a free market economy favors the lowest cost business model as markets mature and price-driven shoppers grow in size. Design a business model that delivers unique benefits, on the other hand, and you must also focus on efficiency. Because customers only pay price premiums for unique benefits, any inefficiency costs come right off your bottom line. Is it any wonder then that on-line retailing is growing by leaps and bounds, steadily gaining share against in-store retail? E-commerce is far more efficient, something Amazon understood in disrupting the book industry. In addition, on-line sales lower consumers’ indirect costs by saving time and gas money and, during the busy holiday season, avoiding the frustration of fighting crowds. Nevertheless, efficiency and convenience won’t overcome frustrating on-line shopping experiences. So how successfully are on-line retailers satisfying the increasingly demanding consumer? Better and better according to…