Part of the problem is predicting week in week out what people will choose to buy. It is far easier predicting spend than it is predicting what would achieve that spend. It also very very hard to predict which products with a short shelf life will sell through. If you have no goods on the shelf you won't sell, if you do have goods then you still might not sell, therefore waste is an unfortunate consequence of modern society. The public prefer and are encouraged to eat fresh, that being the case we must accept some waste, at what point therefore should it be written off?