This has nothing to do with morality. It is purely economic. Amazon makes a decision whether they can afford to absorb this mistake, and gain brownie/internet/k

This has nothing to do with morality. It is purely economic. Amazon makes a decision whether they can afford to absorb this mistake, and gain brownie/internet/karma/customer-service/loyalty points, or that they cannot afford to absorb and in that case they will simply not honor the mistake. A smaller vendor would probably not have the luxury of that option. Economics, really.