Challenge is to prove its fake.
Like you've seen on the thread, Amazon is not accepting returns till you are able to get a certificate from the manufacturer.
Same things happen with other items like shampoo, soap, eatables etc. It's trickier to even prove some of them can be fake since you've to again contact the parent company and go through the grove.
The reddit link I posted earlier goes into this rabbit hole when a guy got rash via a soap bought on Amazon (US), got it confirmed manufacturer that it was indeed fake, and then decided to find out what is happening. It's an issue of recent times, not of 10 years ago, and Amazon has no incentive to stop 3rd party sellers and inventory commingling as YoY they have increased revenues from 3rd party. Most people wouldn't be able to identify fakes anyway, so the reporting numbers are low.