Heffey:...
Where I live in Canada, you cant buy a gun without taking a safety course, you cant operate a boat or PWC without operator card and when I bought my last truck I had to show my valid license, proof of insurance and I had to listen to the sales agent go over all of the safety issues regarding the vehicle. I dont really know about the plane, because in my wacky life everyone I know who bought a plane was a licensed pilot. Go figure.
Heffey,
Things are a little different in the US and state-to-state. I purchased and operate a small (19ft) boat without any insurance or operators licence. It is neither required nor common. You can buy a plane without a licence but you cannot fly it without one. It is actually quite common in the experimental market. We are not required to have a drivers licence to buy a car. The large corporate lot's often require you show one but it is for liability rather than requirement. Proof of insurance is required to get a licence or tags. The only requirement to buying a weapon is that you have the money and do not fail the background check (basically drug, mental and legal restrictions). I can buy an AM/FM transmitter but I need to get a licence to broadcast. The list goes on. By nature US and State laws typically regulate use rather than aquistion. In the US to require a licence to purchase scuba equipment would be to increase restriction to a very select group of commodities which are typically deefense or security related.