Honestly, I don't see self driving cars as happening in our lifetimes. There are simply too many variables that have to be processed, and decided upon too quickly, in an uncontrolled environment, for it to be viable. People want to get drunk, and then have their car drive them home, and that isn't going to happen.

A self flying aircraft however, is enormously simplistic to make. I even have my own that I built last year, you just program in waypoints, and it flies itself. You don't remove the pilot from the equation, and self flying aircraft will generate a series of optimized routes, and the human technician decides which one the aircraft flies. The reason we can't do this now, is because the ATC system requires cross verification of instructions, that a computer simply can't do. Furthermore, the ground based navigation systems are too unreliable to use as a reference, this is simply replaced with on board navigation based on doppler shift lidar. All of this can be retrofitted.

The reason I say we will see single pilot soon is because the aircraft are already made, and currently in service, they just need FAA certification to remove one pilot.