I agree.

In two dimensions, a vehicle moving North-South and a vehicle moving East-West have to cross into each other's path at some point, and 2.5D solutions (bridges and flyovers) help but require significant investment in resources that simply isn't possible at every junction.

In three dimensions, this simply isn't the case; we can separate different directions of traffic by height, and provision of dedicated corridors for changing route is merely a matter of making regulation rather than infrastructure.

There's a reason why we've had autopilot on planes for significantly longer than on cars.