Like get a decent amount of actual, needed food or stay the fuck home
That's unenforceable. What about the people who don't have much money, so don't buy very much? Or when you go to the shop and they still don't have all the things on your list, so you come out with little or nothing and still need to go again? People who shop on foot so have to do it little and often rather than piling a trolley full into the car?
Are they really expecting people to buy a load of extra stuff that they might not need or have the money for to make their trolley up to what someone else considers to be 'enough'?
Unless they start stating an actual of times people go to a shop and publishing lists of what people are allowed to buy people have to decide what they will buy, where from and how often.