Countless solutions have tried to solve the problem of counterfeit goods by using some kind of unique identifier but I don't know of any that has seen widespread usage.

The difference is that Amazon is exceptional at tech and has the marketplace to implement and improve their solution over many years. Hopefully Amazon's solution becomes cheap and easy to use for even small brands (but realistically it only needs to be less expensive than the cost of counterfeits to be adopted).

If Amazon's Transparency is REALLY GOOD, they could offer it as a service through AWS. There's an enormous demand for this sort of solution.