“To level the playing field for restaurants, they could offer half-sized servings for a 40% discount.”
This demonstrates huge ignorance. The eatery goes broke quickly. Food is a minor cost in the restaurant biz. Smaller portions barely change the overhead for the restaurant.
If a restaurant's revenue drops by 40% with the same number of customers they are going to be bankrupt as soon as they burn through their cash reserves - if they have any.
It's not easy to get a landlord to take 40% less rent, and to get the employees to take a 40% pay cut.