A great deal of Amazon's store has moved from the old "customer obsession" principle of the early years to a new principle of "revenue obsession."

Brad Stone's second book about Amazon ("Amazon Unbound") does a refreshingly candid and detailed job of explaining how this switch happened. It's tucked away in Chapter 10, I believe, and it never got as much media pickup as I would have expected.

For me, at least, grasping the extent of this transformation made it a lot easier to understand what I kept encountering.