They have a strong ethic and they stick to it, and it very much comes through in setting the tone of their sites. It's so sad to see so many other companies compromise when you get such a great RoI on little investments. Most sites have shopping carts that expire after a couple of minutes. Amazon's shopping cart lasts effectively forever though. The result is a better user experience at a modest cost of engineering and database resources. It's the polite and correct thing to do, and for amazon it probably results in a just slightly higher rate of sales, not to mention better customer retention, etc.

Ultimately the best companies are those who are passionate about their users and willing to go to considerable efforts to do things which have no other goal but making users happy.