I take it one further and bring in a cart from between spaces, someone is finishing using packing away groceries, or already in the station and bring it back into the store to use. And as a single person struggling with the increasing cost of groceries, trying to keep my weekly trips under 80$. I can carry out everything I get by hand, leaving the cart in the store.

Returning the cart to the station is like bare minimum and still many people can't even do that.

It's surprising to me US carts don't have to be unlocked by a coin (which you get back when you lock your cart again), it's like that in every supermarket I know in France and Germany and probably many other European countries.

You can misbehave but it costs you a little bit, and if you do someone has the opportunity to make a buck off you by cleaning after you.

This should be a do-or-die grade in the finals, globally. And don't let anyone know when or where they'll be evaluated and graded, make'em think the Civics teacher/professor will stalk them around town, putting together their resupply patterns, and grading their mall etiquette. That'll put the fear o'God in'em!

Where I am people do not trust people and shopping carts are coin operated.

What if returning the carts is my usual practice, but there was a time crunch one time and I needed to save myself the extra 30 seconds?

I think the theory goes too far, tbh. If we're being a little bit realistic, a difference between animals and members of human society is that animals cannot and do not obey laws. Higher order animals obey direct threats of punishment, such as if you've trained them not to shit on the floor, but that's not the same as law. With a law, you are aware of the consequences without having directly experienced them.

An animal only respects consequences after directly experiencing them.

I am willing to accept into society those who obey (just) laws without directly experiencing the consequences. They ARE better than animals, they are not savages, they are not bad members of society. They are doing the bare minimum necessary to belong to society; indeed, their existence is the reason we form societies at all. You might not want to be friends with them but they aren't animals.

While the conclusion of this post goes to far, I do think it nails it right in the first sentence: if you return the cart, if you do what is correct without need for a law, then you are capable of being self-governing. You would make a good anarchist, for example, because your social group would function well without laws.

I prefer the Gom Jabbar but the Shopping Cart seems like a viable alternative.

prints this image out a million times and attaches it to every shopping cart I can find

I disagree with returning the shopping cart being an act of free will. There is a lot of societal pressure to do it for some people, or to not do it for some other people. And there is always the risk that someone who you know will walk see you not returning, and tell all your friends about it. Or want if your boss happens to see you? What would happen then?

So yeah, better quickly return it. Better than having to deal with all these unknowns.