The problem, as I understand it, is that Amazon mixes inventory from various sellers as long as its the same product. Or appears to be. It makes sense on paper

The problem, as I understand it, is that Amazon mixes inventory from various sellers as long as its the same product. Or appears to be. It makes sense on paper but obviously doesn't work when counterfeit products slip into the stock. If that's the case, ironically enough counterfeit sellers might actually end up having original products shipped / fulfilled by Amazon, which might add to the confusion, e.g. positive customer reviews on a bad listing.