No way to enforce it. We already have laws about scams and counterfeit products which Amazon does not enforce, even in cases where it absolutely could.
Having anti-counterfeit laws is vastly preferable to not having them. Counterfeiters do get busted, though you’re right that Amazon and the authorities could indeed do more.
I’d rather live in a world where at least some criminals are deterred from selling me a fake fire extinguisher that doesn’t work when my house is on fire.