Same reason airplanes don't fly by just flapping their wings like birds. There's not always a biological equivalent for solving a problem, especially when you take into account human brain's evolution over millions of years. Sometimes computers need more help.
It does seem reasonable, though, that if humans can solve safe driving with a brain mass (3 lbs) that computers wouldn't need that much more help. Put another way: every machine learning "expert" who has a kid is amazed to learn how simple unsupervised learning is and how few training examples are required.