Note the qualfying term "majority". I'd never buy one of the open versions--it's too damned cold in the winter, and too damned wet. Up here in the "great Northwest", we don't need AC , particularly---heat is more essential. But I would bet that AC "will" be an option on the closed versions.
"If it rains so much near your home, why in the world would you want to commute with one of these vehicles? You could get a reliable commuter car (like a diesel-powered Volkswagen Golf) that gets tremendous fuel mileage and still have plenty of money leftover to purchase a slick and fun motorcycle.
Because it will, very probably, get far better gas mileage that even that "diesel-powered Volkswagen Golf", and being closed, be far safer and more comfortable in winter than a motorcycle (which I wouldn't own one of under any circumstances--as I have no desire to bounce my tender cranium off the pavement).
Which said, I oppose both mandatory helmet laws and seatbelt laws, because I think every individual should have the freedom to make the decision to bounce HIS particular cranium off the pavement.
Several of your points make perfect sense...and don't be lulled into believing one of these tiny trikes will be much "safer" than a motorcycle. Any accident suffered in them would be traumatic and ugly. They're only as wide as your shoulders and hips, which is why rugged protective gear would make so much sense.
A VW Golf TDI with the 1.9 liter diesel engine gets mileage that hovers around 42-45 miles to the gallon. I have a friend whose father drove one for years in the early-1990's. When he drove as if he had eggshells beneath his right foot he could squeeze 49 miles per gallon out of it on his highway commutes when A/C wasn't needed. I'm sure the modern ones do even better.
~ Blue Jays ~