If you compare these to planes, planes have airways, and have different flight levels on a same airway (and all the technology you mention + 2 pilots capable of

If you compare these to planes, planes have airways, and have different flight levels on a same airway (and all the technology you mention + 2 pilots capable of using that technology + air control) . If you compare these to cars, cars have roads. Imagine a very large square where cars are free to go up to 180 MpH with the "only" rule that the car coming from the right has precedence, which is more or less what boats/ships do now (but they do this at 0-40 MpH top). Not that the possible issues cannot be solved, but surely there will be the need of a license that - if not directly comparable to a commercial airplane license - will be anyway much more complex than a plain boat license.