A sailboat under power is a Power driven vessel, a sailboat under sail alone is not. So you can turn the wheel over to anyone you want, as long as you're sailing and not motoring.
That is an interesting distinction I hadn't thought of. I wish I had thought to ask the Transport Canada inspector about it. I suspect it doesn't apply in
Canada but might here where the power issue is more prominent in the various laws. For example, I pay excise tax in Maine based primarily on horsepower so less for my 32 foot boat than many pay for small outboards. I'm not complaining.
The " operator" of a motor vessel is no different than an operator of a car.
I disagree on this one. On larger power vessels, whether Aux sail or not, the "operation" may well be a team effort with one person navigating and directing and the helmsman functioning essentially as a verbally directed autopilot. Navy ships are certainly operating like this all the time.
All of this could have been avoided by Canada and the states including one simple concept in the rules. Whoever has legal custody of the vessel by virtue of ownership, charter, or rental, is entirely responsible for whatever happens aboard. This would have been consistent with the tradition of the sea. It contributes to safety by there being one person who knows the buck stops with them and will therefore think more carefully about who should be allowed to steer and who should not.