The author states that even in easy adaptations such as traffic watch we still do not see UAVs and what the author is missing is the cost! Those military UAVs cost almost as much as a private jet in what today using 1950s technology can be achieved for the cost of a used cluncker.
Also, the same inheritable problems that we face fully automating cars, exist in fully automating airplanes. Each is an individual unit and very autonomous with no single 'track' to follow. In addition to this largely autonomous environment you have integration problems, where you would integrate the old with the new automated environment and still be able to offer the same capacity of airspace usage.
As frustrating (and yes it is for pilots too - more than passengers realize) as air travel seems now days. The achievements of airspace utilization in places like New York, Chicago, Los Angeles, Phoenix, San Fran etc is almost mind boggling considering it's used with a mosaic of 1930s radar equipment which honestly can't pin point you to an exact location within a circle of 1 mile around yourself.