Are you sure that this is because amazon rules ion google serps or is it because google serps are as bad as they could be and poeple canīt find anything and go directly to amazon?
IMO, my Amazon sales are doing good because of a combination of the two points you noted. My Amazon listed products are not always appearing at the top of Google's organic serps. Sometimes when I have checked they are towards the bottom of the page. But there is so much crap on Google's first search result page that it would not surprise me if people are scrolling to the bottom and clicking through to Amazon. Unfortunately Amazon does not give us stats to tell where visitors are coming from. However, instead of pissing away money in Adwords I do spend in Amazon's sponsored products. The spend on that advertising suggests it plays a very, very small roll in my total Amazon sales.
Keep in mind that Amazon is a big Adwords spender. Even though Amazon has paid ads appearing for many of my search terms, the ad leads to an unrelated category page where the product people are searching for does not appear. IMO, Amazon is exempt from quality score guidelines in Adwords because of what I see. Those unrelated ads are without doubt diverting relevant traffic away, but if Amazon ever fixes this to point to the correct subcategory URL atleast, or Google begins holding Amazon to the same quality score guidelines as the rest of us, my sales will grow even further.
It is important to note that the real producers and retailers of what I sell begin appearing on page 2+ of Google's organic serps. From what I see, very few people are clicking through to page 2+. This, IMO, is designed by Google as a big push to drive people into Adwords. It drove me into Amazon, which offers a far better ROI then Adwords. And if zombies do not buy, I'm not subsidizing Google's profit targets by selling in Amazon. I still believe dumping Adwords and selling on Amazon was a great business decision - increased profits, less time analyzing Google zombie budget busting traffic which leaves more time to focus on other marketing sources, product development and follow-up customer care.