I went to Niagara falls the other day and they were selling $10 pizza slices, my wife got one. I went to the grocery store across the street, bought a large roll from the fresh baked ones. Got cheese ends and ham ends at the deli aisle, and grabbed salad cup. It cost me about $8 but I got a much better, massive sandwich compared to what my wife ate.
That's a great idea and I would like to see it here, but America has no real laws preventing billions of dollars of food waste, so companies never do anything like this.
Tourist hot spots are insane. I was having a cup of coffee in a small cafe at St. Mark's Square in Venice and it was 6.50€ for the coffee and a 12€ cover charge. Rip-off.