I'm not sure the incentives align for Amazon to use it's absolute best preference algorithm. Note that I have no idea how to make a recommender engine and if th

I'm not sure the incentives align for Amazon to use it's absolute best preference algorithm. Note that I have no idea how to make a recommender engine and if they can make it any better than they have, but I suspect the real value for revenue is to make people think that the algorithm is finely tailored to their tastes, but is really just pushing whatever crap has the highest margins.