Another reason for doing this is to protect property of other people. Sometimes a gust of wind will send an abandoned cart across the parking lot to slam into somebody's parked car. Or even a moving car.
Agreed. This does fall, as far as I am concerned, into the realm of living in society. You don’t have to do things for the “good” of other people, but you want to avoid doing things that could harm other people.
If you see a cart in a parking lot, it could not only get blown into your car, but might hit someone else’s. You can protect your car and those of others by securing it.
If you are in a line of cars going through a light at an interesection and traffic is backed up, you may go through on the green light, but...instead of zoning out and leaving a full car length of space in front of you, stranding someone behind in the intersectionvwhen the light changes, you pull up as snugly as you can to the car in front of you and therefore let them get out of the intersection. Sure, they probably shouldn’t have crossed, but they probably saw the space in front of you and figured you would pull up. Consideration for others. It isn’t virtue signalling. It is the hope that when you get stuck in an intersection, the person in front of you will have the consideration to pull up snugly.