Forget counterfeits for a second. Even trying to find something like an ultrasonic cleaner on Amazon is like straight going through AliExpress. But wait! Unless you're buying a very very expensive lab model all the "name brands" look to be sourcing the same way and adding a label too. So the name brands are AliExpress with maybe better QC and 200% markup. But wait! Even looking everywhere else it's the same situation…
Exactly to the point! It's a recent phenomenon, I still remember I could find anything of a decent quality on Amazon like 5 years ago, but not anymore. Review system is now totally broken, most products are cheap crap. I don't even try anymore. Amazon is good only for books and probably cables.
Even ignoring how badly they package books, Amazon has also had a counterfeit book problem for a while now[1]. Two years later, not much has changed[2].
[1] https://www.inc.com/sonya-mann/amazon-counterfeits-no-starch...
[2] https://arstechnica.com/information-technology/2019/02/amazo...