Last spring Buck and witnessed what we thought was an appalling site. We were at an all-you-can-eat Asian restaurant. Most of the folks there were being relatively reasonable in how they filled their plates.
However, there was a group/family who came in and, literally, heaped their plates. They ate a portion of each plate, pushed the plate aside with tons of food untouched and proceeded to go back for more plates equally loaded. We were amazed that anyone would do such a thing.
We left the restaurant shaking our heads. Perhaps if there had been a "no waste" policy things might have been different.
We were brought up in, as someone already mentioned, "take what you eat, eat what you take" and, I'll add because we were told, "no more until you finish what's already on your plate." Guess that was a different era.