I don't think you're seeing the longer game Amazon is playing here. Yes they could make a small amount of money licensing 1-click to you so you could use such

I don't think you're seeing the longer game Amazon is playing here. Yes they could make a small amount of money licensing 1-click to you so you could use such a system with your user info. But if they only offer the service through the Amazon Payment program than they get your users to use their identity system, they get a much bigger cut of each payment and they get to add info of the sale to their already massive database of user preferences. Which is probably why they offer 1-click via Amazon Payments and no where else. (I'm not saying it's honest or that I agree but it does make sense from a profit point of view)