Seems most people in this thread are on roughly the same page, but here's an anecdote to give you an idea of why people are specifically comparing to the west:
Just today I was walking home from Nakameguro station in Tokyo and saw an orphaned protein bar wrapper on the street. I was shocked, it was the first time I'd noticed obvious trash (most likely not intentionally littered) on this street in years.
While living in Manhattan last year, I grew accustomed to holding my nose when walking past actual piles of garbage strewn about the street. This is not figurative as most people have used this phrase throughout this thread—You simply leave your rotting garbage on the street for trucks to pick up (obviously stray trash would get picked up by the wind and tossed into the air, descending upon Manhattan en masse). Only starting last November did they start using actual trash bins.
There was even a day when I saw multiple public garbage cans lit on fire and kicked into the street (in Chelsea, a fairly nice Manhattan neighborhood). Could you possibly imagine that happening anywhere in Tokyo? It would be news coverage for a week.
For all the nuance and exceptions one has to go out of their way to find when talking about trash in places like Tokyo and Singapore, it's unbelievably ages ahead of New York City, the richest city in the world.