Off the cuff I'd think that they accept it because they view almost anything that causes people to buy from Amazon to be a good thing. They think that most peo

Off the cuff I'd think that they accept it because they view almost anything that causes people to buy from Amazon to be a good thing. They think that most people aren't seeking, or missing, such a feature. That suspicious/especially frugal people who want to see a price history would actively seek such service, and find it anyway.