Why not? These are really expensive cars (especially Model S and X). An $80,000 car that has a life of 500,000 miles is $.16 a mile. This hypothetical NY to Miami trip is 1,300 miles one way. If you do no driving in Miami that's 2600 miles or $416 in depreciation if all miles counted the same (they don't, the first miles depreciate things a lot more). You can easily get a plane ticket for that, two if you look around.

I flew Providence to Miami for $25 each way last year on Frontier. Even factoring in the cost of parking at the airport and the extra hour of driving time from Boston, I spent less than $100. So, yeah, flying can be super cheap.