I shop a grocery store famous for its checkout line. That sent me down a memory tunnel: the man who invented self-service in 1916, the automated store he built in 1937 that failed three times before he blamed the shoppers, and the first barcode ever scanned, a ten-pack of Juicy Fruit. Which is the gum I stole when I was five and got frog-marched back to the Piggly Wiggly to confess.