Causing a mess for legitimate users of the radiofrequency spectrum, and exposing unwitting customers to prosecution is a plus?

To be clear, you can buy equivalent products on UHF CB frequencies locally, that you can use without interfering with ambulance services for the same price.

This is legislation that exists for a very good reason.

buying the thing doesn't do that.

abusing the thing in the wrong region does.

question : why isn't this a matter of national import/export control? Why is that duty falling onto Amazon?

if Amazon was selling black-tar heroin I would have more questions than "Why is Amazon selling this? How dare they."

Because Amazon has a legal duty under consumer law to only sell goods which are fit for purpose, be of acceptable quality etc. It would be hard to describe a thing that is unlawful to use in the market it was sold as being fit for purpose.