How Did We Ever Let Humans Drive?

Imagine giving hundreds of millions of people loaded guns to carry around every day and shoot past each other, hopefully aiming to miss. Besides simple human error -- slip-ups, dips in concentration, miscalculations, etc. -- we've also got deeper flaws -- rage, uncontrollable emotions in general, poor judgment, irresponsible drug use, etc. We've basically taken one of the most volatile, unpredictable, chaotic things we know and given it control (whatever that word means) of something very deadly, several hundred million times over. If computers had been around before cars, no one in their right mind would have ever let a human get behind the wheel (there wouldn't even be a steering wheel to begin with). Traffic also would never have existed. Just imagine...