The retail business, especially in the world of massive eCommerce and brick and mortar giants, is hard. Margins are thin and competing on price, in addition to selection and convenience, makes growing those margins a challenge. In fact, it's not really any easier for the giants to grow margins either. Amazon's most profitable business isn't retail, it's technology. Building the world's largest eCommerce site required cloud based commerce and supply chain services that did not exist at the time Amazon was scaling, so they built them.