GPS based geo-fenced highways in the sky.
There's no other way.
There must be some resemblance of order. Watch a star-wars movie or similar sci-fi such as Back to the Future 2 to see the concept in action.
You can't just go from point A to point B, it's just not going to work well..... how a road works on the ground it will work in the air. You'll still have intersections and you'll be computer controlled, but moreso for proximity.
PS. Which is morally worse - using a fake rego to avoid landing fees, or not making radio calls at all to avoid them?