Cycling in Canada

[Nouvellecosse]

With aircraft there needs to be significant separation between each vehicle since a) very minor collisions that would barely be fender benders on the ground can easily result in a crash for an aircraft, b) any crash is much more likely to result in damage or injury to people and property on the ground c) aircraft just can't be controlled with as much of precision since air is so thin and constantly moving. Various types of winds including updrafts and downdrafts caused by tall buildings or just various weather phenomena cause aircraft to deviate from their intended course sometimes by several metres in split seconds. That's one of the reasons why the seatbelt sign is always on during the takeoff and landing phases of a flight. The air near the ground is very turbulent since wind is powered by heat rising from the ground and air interacts with lots of objects and textures near the ground while it generally flows much smoothly and predictably at high elevations (with exceptions).

All of which means that it isn't practical to have a high density of aircraft operating in close proximity to one another. But that's exactly what you'd need to carry the large volumes of people needed to be useful in solving urban congestion. You might have small numbers of very wealthy people using aircraft to escape congestion like in Sao Paolo, but that's not useful for mass adoption. And of course that ignores the fact that aircraft tend to be much noisier than land vehicles so filling the sky above a city with low flying aircraft would result in horrific noise pollution. And it also ignores that aircraft use much more energy than land vehicles since they're not only propelling themselves horizontally, but also use energy to support their entire weight vertically. Which is why we generally only use aircraft for long distance travel. So while I'm sure there are niches in urban settings where "flying car" type stuff would be useful, mass implementation for general urban travel isn't one of them.