Excellent analysis. But the issue here isn't that someone made a mistake somewhere.

But rather, that at a very high level: Amazon knows perfectly well that a certain percentage of its customers are getting screwed over, just as it knows it could probably do a lot more internally to prevent this kind of stuff from happening. But having sat down and done a "rational" cost-benefit analysis -- it has calmly decided that it plainly doesn't care, as long as it thinks it can get away with it.

That's just the way the company is - from the highest levels down.