I also think a valid license for the desired band/service should be required to buy a radio that transmits on that service.
I absolutely, vehemently, disagree. Even if you could make it work for new radio sales (and I still disagree with that) how would you handle used radios? And what about home brew or kit built radios, how would those fall in such a regulated acquisition market?
If I sell a radio to Joe Bag Of Donuts and he shows me a fake license (anyone can print one), should I be held legally responsible for selling to an unlicensed person? Should we also do background checks to confirm license status before we sell used radios? Perhaps we should only allow radio sales, new and used, at and through a licensed radio dealer to insure compliance?
It is already illegal to transmit on a frequency or in a service for which you are not licensed. Adding another level of regulation would not make it any more illegal, it would only increase average cost and procurement complexity.
How many ham radio operators have purchased a radio while studying for the test and before they were licensed? How many have been kept curious by monitoring the radio? Sure, a few bootleg before they are licensed, and a few more never get licensed at all, but in general being able to buy radio gear without a license has encouraged many people to the hobby.
I know I built my first transmitter before I had a license, while I was studying for my Novice ticket. If I had not built it I would have bought one, either a kit or pre-built, during the same time period. Having that station waiting was something that spurred me along in my studies and practice. When my paper license arrived I was ready to go, and made my first contact that night.
One of the basics of US law and history is that generally you are responsible for your actions. This means we are free to own many things that citizens of some other nations require permission to own. You can buy a car without having a drivers license, it is up to you to not break the law by driving without a license. You can buy a semi truck without a CDL, it is up to you to know if you can drive it or not. You can buy an airplane without a pilots license, it is on you if you try to fly it illegally.
The end user is responsible for his/her actions, not the person selling them the hardware.
T!