Can a Candy Bar Price a Code Review?

In the mid-1990s, ten daycare centers in Haifa had a problem: parents showed up late to pick up their kids. A teacher had to stay late every time, unpaid, waiting. So the daycares ran an experiment. Six of them introduced a small fine for picking up more than ten minutes late. Late pickups didn’t go down. They roughly doubled, and stayed doubled even after the fine was later removed. Why it…