Read Kristine Kathryn Rusch's take on the matter HERE.
In my opinion, Sears took too long to get on the internet selling train. The train that Amazon has infinitely mastered with their price matchings, speedy delivery, intuitive algorithms, and forward thinking.
Amazon is undoubtedly a juggernaut in the sales industry, and they became that way by building an empire, then using that capital to come up with new ways of reaching customers. They focus on customer satisfaction and spend a pretty penny doing so. They even opened up the market for independent sellers and authors with Amazon Sellers Central & Amazon Advantage programs and KDP (Kindle Direct Publishing). Let's not forget Amazon Associates affiliate program!