Why Amazon.com pages having a good ranking on Google Search?

On Webmaster Central Channel on YouTube ,Matt Cutts answer one question which is:
“Why do Amazon.com pages tend to rank well for product queries?Search for a physical product usually ranks Amazon #1, even though it may not provide the best user experience. What is being done to prevent large corporations from dominating search engine results? Steve K, Pennsylvania”

Here is Matt Cutts Answer:

According to my practical experience’s domain authority,link popularity,end user satisfaction(including review,social metrics) are key determinant’s for successful product page on Google search.

Started By Anirban Das,Zebra Techies,India