They both fulfill the same purpose from Amazon's perspective: driving sales. Amazon has always been driven by volume. Get enough of it, and no one else can sur

They both fulfill the same purpose from Amazon's perspective: driving sales. Amazon has always been driven by volume. Get enough of it, and no one else can survive. From that perspective, selling ad impressions is... tangential. So they make "a few" (billion) on the side, it doesn't further their primary business. Whereas Google or Facebook without ads would be... what?