You make good points, but I'm not convinced this isn't deliberate on the part of Amazon. First, Amazon deliberately keeps buyers in the dark - e.g. sellers can pay extra to avoid comingling, but Amazon gives buyers no way to find this out. Second, this kind of reckless approach to fakes is what enabled Amazon's rapid growth over traditional retailers with hand-picked, verified goods. It's not surprising they try to sweep problems with their approach under the rug.

Perhaps not 'complicit', but with a reckless disregard towards fraud.