While I agree about the hope for this being a solution to mass transit in urban areas...
Cars don't merely require "space", they require space that has road on it with tarmac and signs and lights and junctions, and they require it in a limited 2D plane and that is the same 2D plane that we need space for buildings etc.
Planes work in basically any space and require no infrastructure.
There is a metric shit tonne of space for planes right now just waiting for use. The same is never true for cars.
You got it wrong. Airspace over cities is very limited. At some point you get to the height in which long distance flights travel.
Also, all aircraft have a minimum required safe distance between them tht needs to be large due to aerodynamics. This it become physically impsible to increase traffic density beyond a certain, low threshold.
Cars don't merely require "space", they require space that has road on it with tarmac and signs and lights and junctions, and they require it in a limited 2D plane and that is the same 2D plane that we need space for buildings etc.
Planes work in basically any space and require no infrastructure.
There is a metric shit tonne of space for planes right now just waiting for use. The same is never true for cars.