Its based on my opinion that you can't really keep the junk out of the US and the only enforcement would be after the product has been placed into use.
If you can keep the junk out, that would be great, but I just don't see any such law being passed, or if passed, I don't see it being enforced at the import points.
I agree, enforcement is always difficult, but it's not entirely out of the question, especially if you go after the producer/importer.
Look at the FCC and FDA. Enforcement is quick and harsh.
Through up a WAP running an overpowered transmitter on a DFS channel close to an airport and you'll get a knock on your door within hours likely.
The Christmas lighting groups I follow, there's a few stories a year about the FCC knocking on doors asking questions about their FM music transmitter because someone complained it was blasting over their Polka station.