It's also fairly common when I have to enter an office building or other facility where somebody at a security (or "security") desk inventories all entering and exiting laptops by serial number. Owners of laptops with easy-to-find and easy-to-read serial numbers breeze right through both ways. The few brave (foolish?) Mac owners like me have a much, much tougher time. Me: "There's the serial number in teeny, tiny print. See?" No, the security officer doesn't see it. Virtually nobody does, not without a magnifying glass. Of course there's no magnifying glass or it cannot be found, and then "hilarity" ensues at the security desk.
Or I suppose I could power up my Mac (if not already powered up), unlock my Mac, go to the Apple menu, select "About This Mac," and show the security officer the on screen serial number. And I could do all that in the "alien" place with recording cameras everywhere, with some unknown security officer ready to grab my laptop? No thanks.