The waste in some restaurants is amazing.
For example some places take left over fried chicken and make chicken salad for the next day, either for a special or employees meals. Others throw it out.
One of my favorite customers was a Holiday Inn that served a buffet at lunch. I always managed to make this a stop at about 1:30. Breakdown time for the buffet. Fried chicken, roast beef, pork roast, veggies all were going into the garbage. Nothing was saved. I would load up four or five go boxes and the dog and I ate well for days.
This was one of worst examples, but plenty more were like that.
I have seen one of the hotels throw away a couple hundred salads that filled a large garbage can. Don't know what happened, but they were a little old. Could not be served (little browning of the lettuce) but perfectly ok for Wayside for someplace like that.
Of course a lot of places or much more frugal that this.