Amazon itself has admitted it has a counterfeit problem to it's investors
https://qz.com/1542839/amazon-has-finally-admitted-to-invest...
Beyond that there's been documented cases by manufacturers such as Birkenstock and Apple plus the eclipse sunglasses.
One aspect is that not everything has counterfeit counterparts, e.g. there is no counter-counterfeit to, specific counterfeits, products that require exotic parts, or foods.
I’ve never seen a 4-cell(Lipo) knockoff battery for Lenovo X200 and I know the reason is because it is not easily possible to source appropriate components.
So there could be specific usage model for Amazon of a person that could completely avoid receiving unexpected items.
https://www.npr.org/2018/09/16/647377213/fake-bike-helmets-c...