A few years ago I bought a $15 audio amplifier on Amazon. It failed a little while later and after a bit of googling I found a page from the manufacturer about

A few years ago I bought a $15 audio amplifier on Amazon. It failed a little while later and after a bit of googling I found a page from the manufacturer about identifying counterfeits which were apparently rampant. Different PCB layout etc. Amazon does have a brand registry which manufacturers can opt into and then actual proactive counterfeit enforcement will happen specifically for that brand. Some but not all items in the program have unique per-unit barcodes that Amazon verifies and customers can too through an app called Transparency. But as a customer you have no way to tell which brands are enrolled in the program unless you receive the item and see the Transparency barcode on it.