I think this kind of thing should be reported to mass media somehow. That's about the only way that non-collectors will ever get the correct information. We here can easily recognize these types of scams because we are active and knowledgeable collectors/dealers/sellers, but the "general public" won't have access to what we know unless they stumble on one of the forums.
And that is when they get their education. IF it was made after 1973. Copies made before 1973 do not have to be marked (HPA does not apply to items made before it went into effect.). The question is, how do you know when they were made? Perfectly legal to buy them, illegal to import them into this country. If you are outside the US, sell them and have them drop shipped from China, the only person breaking any laws is the buyer.
But if the seller isn't in the US, then our laws don't apply. If they are both in the US then I could agree with you.