Earlier quoted context omitted.
There are plenty of places in the world where littering is not socially acceptable and happens less than other places. What is the difference between these places? I think it's the people, not the material their garbage is made of.
Well, there's Singapore and...? That's about it. Of course as well as extreme and draconian legislation, like banning gum, they're a tiny city-state. Yet Singapore employs vast numbers of cleaners and street sweepers clearing up - which surely shouldn't be necessary? Far more per-capita than any Western city. So even they seem to recognise it will happen anyway.
When traveling, I've been impressed by the cleanliness of Zurich, Copenhagen, Helsinki, and several cities in Germany.
If as a society we can't do something as simple as not throw garbage on the ground, I think we have a very bleak future.