You go to the store to get one thing. You tell yourself "I don't need a cart". You get to the aisle, find what you want, you pick it up. It's heavier than you thought, but you can manage. However, with every step up to the check out, it weighs you down more and more. The relief is palpable when you set the item down to ring it up, but with the transaction complete, and the return journey to your vehicle before you, you ask yourself once more; cart or no cart?
No. You've come too far. It's now the principle of the thing.
