Mine is there as a legal disclaimer
Edit/ I also have the second part because it is a pet peeve of mine and I really believe it is true. You either have the sense of responsibility, decency, and respect for others to put the shopping cart somewhere safe after loading the groceries into your car, or you think that your 30 seconds of time is worth more than blocking a parking space, scraping other people's cars, making some poor high school cart-boy's life misery, and sending carts rolling off into nowhere-land.
It is a simple thing, which makes it even more telling of someone's character!
BTW, the lowest of the low are the ones that put the cart in a
HANDICAPPED PARKING SPOT!