I don’t do this, and I do feel your frustration at waste, however it is a problem largely caused by the stores themselves. The whole notion of a super market is size and economy of scale, the whole idea was to reduce service and staffing levels by letting the customers in to pick their own items, carry their own items, calculate their own costs, and now, check out their own items, pack their own items, and process their own payments, much of the time without any interaction with a member of staff. Our nearest supermarket is the size of an aircraft hangar. Supermarkets invented huge shopping trolleys. They invented and promoted the idea of a “weekly shop”. We do not know the people who work there. They do not know their products or what they do, or what to recommend for you. They often do not know where things are or what is sold there (understandably, it’s huge). Food waste is increased hugely by the size of the store, the lack of human interaction - not guilting people into buying something but by being able to guide them to the deal/item in the store that they want, and not requiring them to walk two football pitches there and back with a fully loaded and wayward shopping trolley to put a pizza back. It’s done in the design of the store - hiding cheaper items away or frozen sections at the back. It’s done in the idea of shopping just once every seven days, so food is not as fresh when we eat it, doesn’t have as many nutrients, goes off faster, tastes worse. We are encouraged to buy something six days before we are due to eat it and then we must have it because it needs eating, whether we want it or not. They encourage food waste by selling things in packs of four, eight, ten, to families of three, six and nine,
if we could shop in smaller shops, with people to answer questions about offers, stock and fresh produce, if we could shop in a couple of minutes instead of a couple of hours - walk in, ask for things needed, get them prepared as we need them in the quantities we need them. Buying things as we want to eat them, seasonally, when our bodies are telling us we need a certain type of meal and not the type the “meal plan” or use by dates are telling us we must eat. This would not happen. It would reduce food waste on every level.
It is a very annoying feature of a huge set of problems caused mostly by the very idea of a super-market.