A thing about "we were promised flying cars" is people have constantly been inventing flying cars for near a century now, they...
A thing about “we were promised flying cars” is people have constantly been inventing flying cars for near a century now, they are inevitably worse cars than dedicated cars, worse planes than dedicated planes, and more expensive than one of each.
Like, pretty much every part of the power transmission/propulsion system after the internal combustion engine is completely different and heavy. There’s stuff like – small aircraft engines don’t use auto-style spark plugs, they have dual magnetos that you test preflight on the runway every time so you’re sure they won’t both fail simultaneously. Like, “there is an enclosed compartment where people sit facing forward” is kinda the limit of what they share in common.