Why are wealthier areas cleaner? Is that even the right question?

My store draws from the wealthy, middle, and poor parts of town. Our sister store is in a middle-to-wealthy-but-mostly-middle area, as are my preferred grocery stores.
On my way to break I realized that there was an awful lot of stuff scattered around where it shouldn’t be – canned spaghetti on top of a pallet of small appliances, one of my loathsome chickens in the pharmacy, a bottle of perfume in the cold case, and the odd napkin or sample cup tucked between products or behind shelving or just anywhere.
I thought about it, and realized that I never see that sort of thing at the other stores that I’ve mentioned, and concluded that it’s probably the difference in clientele, and got to wondering:
Why?
Why is it hard for some people to replace things that they don’t want, and so easy for others? What’s so difficult about tucking that napkin into your pocket until you find one of the four dozen trash cans that we have scattered around? Who refrigerates perfume, anyway?

What makes a person disinclined to not make a mess out of everything? What kind of person is that discourteous, and why?

Does it come down to simply getting someone to clean up after the army of Pigpens?