The code has to be logged at Amazon warehouse though so it can linked to your amazon account number. Manufacturer -> Distributor -> Customer. Otherwise I could buy one real product off Amazon, copy the code onto my fake product and sell on Amazon marketplace.

Cuban cigars have this: http://verificacion.habanos.com/

The biggest issue is with people taking authentic packages, filling with fake cigars and selling it.

The problem is that you don't know if it is counterfeit until you get the item and scan the code. That's only marginally better than the status quo -- most counterfeits on Amazon are rather easy to spot once you have it in person.

With Amazon's program, they can do it when they accept the shipment and potentially destroy the entire stock of the seller's wares.