A lot of times litter is not from littering. A home trash can's lid blows open in a strong wind and litter flies out. Trash escapes from an urban trash can. Trash flies out of the back of a garbage truck, etc.
The biggest cause in my neighborhood is the pickup process itself: the machine lifts the can in the air, turns it upside down, shakes it, and hopes that it all makes it into the truck.
A lot of smaller stuff doesn't make it in, especially disposable plastic bags, which are basically little parachutes.
I don't know, I haven't spent much time there and have only visited 3 major cities. But in each it was evident that they prioritize cleanliness and order, so I might guess that they generally use cans with better lids.
At around 9pm in downtown Tokyo I stopped to watch a clean up crew scrubbing something of the sidewalk. So perhaps it's partly due to where their tax money goes.
To be clear, I asked this question because I was considering the claim "a lot of times litter is not from littering." It occurred to me that, if this were true, you would expect culture to have less of an effect on the amount of litter in a particular city.
I suppose tax dollars and trash can technology would also be a plausible explanation, but it leaves me less convinced.
