I would argue that the intentions don't matter at all, the end result is all that matters both for the buyer and seller. In systems design, it is often said that The Purpose of a System Is What It Does. Good intentions can produce very bad systems with bad outcomes, and neutral/bad intentions can create good systems that benefit everyone.

I think that applies both to Amazon's dev system and pricing system. From what I hear about the insides, alignment is chaotic neutral inside of Amazon, but that shouldn't affect how we judge the system itself.