I love the flying car example because it reveals a huge issue with the whole “tech will get better” idea. People are still trying to make flying cars happen but it’s running in to the same fundamental issues; large things that are mechanically complex, energy intensive, and moving at high speeds in a crowded urban environments are just too expensive and dangerous.

There is no way around the physical realities, no clever trick or efficiency that will push it over some threshold of practicality.