I don't agree with the assertion that fake reviews don't benefit them, but I may be missing something. Reviews help drive consumer behavior and more reviews lead to more sales from those who are unable or unwilling to be more discerning. (Amazon takes a cut)

For others, it the idea or presence of fake reviews might drive them to a "trusted" Amazon Basics alternative, also leading to sales with a higher margin for Amazon.

Additionally, recycling listing ASINs is a common tactic that Amazon could stop and is a source of "fake" (or at least, irrelevant in content and misleading in score) reviews. There's minimal enforcement of rules for review integrity, such as verified purchases or quid pro quo "warranties" and "free gifts" for 5 star reviews.

All the evidence I see points to Amazon preferring the status quo.

"Brushing" scams seem way too common and easily executed through Amazon in order for them to not be turning a blind eye about it, imo. My mom was sent random LED lights for months through their return program despite never ordering them or hardly using amazon at all before she figured out what was happening. It feels like at least 5% of all my purchases come with a policy breaking email from the seller contacting me asking me for a five-star review in exchange for a free gift. Or even just contacting me 6 months later from a totally unrelated purchase and offering me a gift for no reason in exchange for a five-star review. Oh, they'll sure reimburse the money it costs to buy it! Because they really just want that five-star review! And Amazon seems to be happy allowing five-star reviews for products that are given away for free and even has a tag to let other users know, but just this method is frowned upon? I doubt it.