The problem "flying car" was incorrectly described as an aeronautical engineering problem — as if inventing a compact, two- to four-seater aircraft that needed only a short runway — and ideally could use highways — was the hard part. Well, ultralights and roadable aircraft have been invented.

The problem is one of turning the invention into a transportation system ... and that's a different problem, involving safety, automation, and policy too. It turns out that bad pilots can do a lot more damage than bad drivers, for instance ....