Though the difference between a supermarket checkout and an airplane is once you're through the checkout, you're free to leave.
You don't walk out the supermarket door and have to wait for a hundred people to load their cars and make their way out of the parking lot. Which means that getting you through the checkout faster just means more time waiting to get out of the parking lot.
You don't walk out the supermarket door and have to wait for a hundred people to load their cars and make their way out of the parking lot. Which means that getting you through the checkout faster just means more time waiting to get out of the parking lot.