aircraft have a less chance of collisions or other accidents than ground vehicles, and less natural obstacles that their program can misinterpret. autopilots of varying complexity have been in commercial use for decades. Even if you're physically inside the robotic aircraft the chance of failure-even if it is catastrophic-is small with respect to the robotic ground car or bus. Most of us deal with this kind of risk daily anyways. As for the chef and the spouse, so much can go wrong that would be hard to anticipate in the engineering phase. And when something goes wrong either your digestion or your genitals are on the line. Definitely not in my comfort zone.