Most travelers want the cheapest flight they can find. Airlines, meanwhile, need to manage volatile fuel costs, a pricey workforce, and complex logistics. So how do they make money — and how did America’s grubbiest airport suddenly turn into a palace? (Part 3 of “Freakonomics Radio Takes to the Skies.”)

In this special episode of People I (Mostly) Admire, Steve Levitt talks to the best-selling author of Sapiens and Homo Deus about finding the profound in the obvious.