Sell By dates are a bit cause of the wasted food problem, along with our "big once a week shop" habit, and 'family bags' of perishables and BOGOFS (20 oranges for a quid might be good value, but will you eat them all?). And not using lists and planning our menus.
People buy tons of food at the supermarket on a Saturday, don't always check the dates (which are largely advisory not mandatory), shove it all in the fridge where half of it goes off before it gets eaten.
I've never had money to waste, so I plan my meals, buy just what I really need, and don't buy stuff that I know I won't eat.

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~ What do I think of Western civilisation? I think it would be a very good idea ~ Gandhi