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 ~
Sorry---disagree. The "exoskeleton" design of the framing lends itself perfectly to a great "roll cage". Would work just like the safety cages on dragsters.
"A VW Golf TDI with the 1.9 liter diesel engine gets mileage that hovers around 42-45 miles to the gallon."
I'd guesstimate that a gas-powered buggy like this with all the computerized tricks would probably get twice that. It would certainly get better gas mileage than an equivalent motorcycle (I'm talking a "closed version") due to reduced aerodynamic drag.