Remember how -- for decades -- the airlines would ask if your bags had been out of your control any time after packing them? Yeah, it's engrained in people that they can't let their bags leave their sight.

(Once I was checking in for a flight in Puerto Rico after disembarking from a cruise, and I answered that question honestly. Based on their response, I was the first person who had ever done so, despite the fact that every major cruise line requires you to put your luggage outside your door the night before returning to port, and you're reunited with it once you get off the ship. Tens of thousands of people do this ever week, then fly home, and I was apparently the first one who admitted to it to the airline employees. They were completely flummoxed, and didn't know how to respond.)