It was widely reported, including with graphic video, that a pedestrian in Arizona was recently struck and killed by an Uber self-driving automobile in the testing stage. A secondary story to emerge from this tragedy has been questions about the overall safety of self-driving cars. Some companies have temporarily suspended the testing of their autonomous vehicles. Arizona put the brakes on allowing Uber to test such vehicles on public roads.

For the past several years predictions have abounded that widespread use of self-driving automobiles is on the horizon. These vehicles promise numerous safety features. While automobile manufacturers long-ago conquered cruise control, and blind-spot monitoring is an impressive innovation, I’m dubious that drivers will ever be playing Yahtzee on the way to work. In two centuries nobody has been able to eliminate train derailments. And they ride on a track, and usually with no other trains nearby.