That is a very generalized statement. I have bought hundreds products shipped and sold by Amazon and never had an issue with authenticity. I'm sure it happens, but I'm willing to guess it is pretty rare and Amazon has always been quick to refund products that are shipped and sold by Amazon.
I gave up after the third time and went back to buying from brick-and-mortar, and haven't had a problem since.
Between my experience and reports from others, I'd say that you've been extraordinarily lucky.
Other gear (filters, nose cusions, tubing) looks more or less authentically packaged correctly.
Some of the fake stuff is pretty good. Would you notice if your energizer batteries were random Chinese fakes?
The first fake I discovered on amazon was a mouse trap of all things.
My friends and I all bought fake Bose headphones from a shady dealer in China (in person), and the $50 knockoffs sounded exactly as good as the real $600 ones. The only way to tell there was anything wrong was by the fact that they all broke down within a few months.
Workers will “divert” product from factories (or almost) finished product and sell on the side.
I’ve heard this is a big issue with clothing manufacturers.
Of course determining whether it’s actually counterfeit or just diverted product is likely impossible at the point of purchase.
He’d buy “grey market” gear from stores in NYC that were legit, but intended for Latin America or other markets. Sometimes the fit and finish would be interior or connectors would be lower quality, but the price was right and an 80% product is better than nothing.
If I know I’m buying a “Rolox”, that’s one thing. If you sell and price a Rolex that is not, that’s a problem.
I probably wouldn't care about a mouse trap though, as long as the mechanism doesn't store enough energy to burn my house down.