Consider that the average person, plus luggage, weights let’s say 250 lb. This says the average car weight seems to be 3,000 to 4,000 lb. http://cars.lovetoknow.com/List_of_Car_Weights So, you need to charge the equivalent of roughly 15 airline tickets to ship a car. What’s that? about 1/3 the retail value of the average car? Say $10,000 for a typical trip? My parents paid substantially less than that to ship their car (by ship…) to Europe for a sabbatical.
However, the devil is in the details - if an airline overbooks a few seats, well, no great loss - they pay a few people a bonus, they usually get on the next fight. How many ferry flights would there be from, say, Chicago to Miami? being bumped with car would be a far bigger inconvenience - so they’d only sell guaranteed spots. the people who are paying $10,000 or more to have a car at the destination probably don’t appreciate being made to wait. meaning there’s a good chance the aircraft would fly partly empty, so the price for the rest goes up comparatively. People who can afford to spend $15,000 to have their car present, can probably afford a very good car and driver hire instead. If it’s an extended stay, a car service will drive it down for a helluva lot less.
Then there’s handling - a ferry plane is not easily converted to passenger only, so it’s dedicated to that . A 737 for example, holds 150 people. Can you fit 10 cars in it? Would need somewhat of a redesign. (IIRC the 70’s series “The Magician” featured Bill Bixby as an independently wealthy prestidigitator who had a private 737 with a one-vehicle drive-in garage.) Then there’s the issue of gasoline fumes and fire risk, tie-downs, etc.
You better have a really expensive car if you want to pay so mch to have it on hand for a short trip.
I see this only as an option for really rich people on awkward travel legs- let’s say, England to Dubai. Rail or self-drive don’t really work as options, shipping would take a much longer time. but then, those guys can afford a Rolls at each end and long-term parking.