There's much data to confirm Amazon knew, for many years. In addition, Amazon allowed vendors to directly contact customers to coerce 5 star reviews in exchange

There's much data to confirm Amazon knew, for many years. In addition, Amazon allowed vendors to directly contact customers to coerce 5 star reviews in exchange for products, and Amazon did not require those reviewers to disclose their review was solicited and not completely voluntary. I've received those emails, as have my family and friends, for at least the past 3 years.