Unlike their policy around the use of the word "Cuba",
ebay cannot put a blanket ban on using the word "replica" in its listings, since replicas of non-coin-related things are perfectly OK to sell on
ebay. So
ebay's first line of defence - the word filter - is powerless to stop the fakes.
ebay does not, unfortunately, hire an army of people to eyeball every single listing. It relies on reports from other
ebay users - their second line of defence.
Unfortunately,
ebay no longer actually hires an actual human to look at these reports - it uses an AI. A particularly inept AI, since it too does not seem to correlate the presence of the words "fake/replica" and "coin" in the same listing as triggering some kind of policy warning, like it does for regular humans. This can
give the frustrating experience of
ebay's AI telling you "nothing is wrong" when there very clearly and evidently is something wrong.
ebay's third and last line of defence is a cartel of trusted "experts", whose reports of fake coins bypass the usual AI filter and go straight to an actual human in
ebay for direct action. These experts are not
ebay employees, but volunteers, so their reporting is therefore haphazard and non-systematic. Some of those volunteers are right here on CCF.
In the end, your observed situation is not entirely unlike what I observed when I visited America a year ago: everybody on the interstate was speeding, despite the clearly posted speed limit signs and laws preventing speeding on the statute books. Is speeding legal on American highways after all? No, of course not - but the police can't be everywhere and simply don't have the resources (or the constitutional authority) to implement a truly effective fully automated speeding-driver-detection-and-elimination system. Ergo, lots of people can easily be seen breaking the law, despite the law remaining in place. And if you do get pulled over by an actual cop for speeding, "everybody else is doing it" is not a valid excuse.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis