Most diners have a “Seniors” menu as well as a children’s menu with smaller sizes.
Most fast food joints have smaller portions in the in value menu. Wendy’s Value burger is half the size of the smallest burger you could get at a Wendy’s in 1975. The Whopper was once 1/3 pound, and is now slimmed down to 1/4 pound.
The one big difference between then and now is the “all you can drink” fountain soft drinks. The better discipline is to opt for unsweetened iced tea as your beverage.
If there is a fixed cost to the restaurant for seating, service, utilities, taxes, rent, then it makes sense to make larger portions a better value, even if the patron takes a doggy bag home.
The supermarkets promote 7 oz cans of soda, 100 calorie version of snack cakes and chips, and they cost a LOT more per ounce, and don’t appear to sell all that well.
Lunchables fill this guy’s bill, but they are overpriced junk, too.