Earlier quoted context omitted.
This is similar to the Japanese concept of Shitsurei (失礼, しつれい). It is of course impossible to comprehend this unique idea that no other world culture has ever conceived of. What a remarkable society!
I did chuckle a bit, but the idea of mottainai is just way more prevalent within Japan, compared to Western countries. I can't speak for other Asian countries, but it's very easy to feel that compared to North America and Europe (places that I've lived in). Funnily, I've felt it in post-soviet countries as well, but that's coming from the feeling of scarcity in the beforetimes.
US however seems pretty unique in its not caring about waste. Heck, it's really tough not waste food because all servings in restaurants are for 3 people so unless you bring everything in boxes you'll be wasting things.