Comment by kakooljay

Interesting post (I love Steven Levitt) but there's a great lesson for developers here: Efficiency is only one consideration. What about usability? Do you really want to wait in line at McDonald's or Starbucks while someone (maybe a high school dropout) counts on his fingers to make change in 71 & 37 cent coins? The overhead here (an extra coin in your pocket) is well worth the added convenience. Aggregated over the whole economy, those extra seconds would literally be worth billions of dollars a year..