The shopping cart theory, as written here, starts as a litmus test for whether a person is capable of self governing and descends into two paths:

1. If you do return the cart you are doing it out of the goodness of your heart and because it is correct; and
2. If you don’t you are no better than an animal, a savage, who does what is right only because there is a law in place or you are forced to.

Self-governance: Are you a good person or a monster? There is no middle ground.

I return the shopping cart entirely out of the fact that ai fucking hate it when people leave the cart in the parking space. But yeah if theres a concrete sidewalk or something I may leave it there if the return area is a row of cars away.