> Anything coming directly from a customer is probably refutable. For example, the incentives I normally see are on these little cards they include with the product encouraging reviews in exchange for a gift card or something similar. What's to stop a competitor from falsely reporting it using a fake incentive card they created?
Maybe the two of you have different definitions of "irrefutable." If I say, "They ship packages with cards in them that offer a gift card in exchange for a five-start reviews," I would personally call the presence of such a gift card offer, irrefutable proof.
True, my testimony alone is not irrefutable proof, but let's compare to a science paper. It says they have proved that light's path can be bent by gravity. Well, science papers have included outright frauds before, so the paper in and of itself is not "irrefutable proof," but the claims within it can be refuted by attempting to replicate the experiment.
And so it is with the gift-card-offers. A single report or tens of thousands of reports are not irrefutable proof, but they explain how to replicate the result, and if Amazon choose to ignore these reports rather than attempt to replicate what they describe, that is on Amazon.
Ultimately, everything a customer reports can be faked. Businesses that ignore customer complaints because they might be faked, and do so when it "happens to" make them money to ignore customer reports... Are not suffering from being unable to prove that the reports are correct.
They are suffering from making too much money to want to know whether they are complicit in fraudulent behavious on the part of their partners.
Yes it is work to find out if the customer is describing an irrefutable way of discovering whether the customer is telling the truth. It is not the Universe's responsibility to make cracking down on fraud easy: It is Amazon's responsibility to organize their business around not making easy money at the expense of their customers, and if cracking down on fraud is too expensive, it is on Amazon to change their business model.
"It's too much work to crack down on fraud" ought to be rejected as an unacceptable thing to say about any business.