When I was sixteen, I had one of those classic first jobs that teaches you more about capitalism than calculus. I was a cashier at Publix. In the 1980s, this was a solid teenage gig. You wore the polyester green uniform, smiled like it was your job—because it was—and never let a customer lift their own bag. Publix was known for customer service that bordered on spiritual devotion.

One day, a customer had a bag filled with four two-liter bottles of soda. I picked it up to place it in their...