1. Overstocked product displays:
Most grocery stores operate under the assumption that customers are more likely to buy produce if it’s from a fully stocked display. This assumption leads to overstocking, as well as damage to items on the bottom of those perfectly constructed produce pyramids.
2. Expectation of cosmetic perfection:
Customers have been trained to expect perfect, identically shaped produce. Retailers stock their produce according to that expectation — even if the shape, size, and color have nothing to do with quality.
This preference leads farms to avoid selling the so-called “B” stock to supermarkets. Whatever does make it through the cracks to store floor is taken out of stock.
3. Sell-by dates:
Most consumers have no idea what expiration dates, sell-by dates, use-by dates, or best-by dates mean. Consumers (and many sellers) wrongly assume that food is no longer good after these days. Instead, sell-by dates are guidelines for sellers to indicate peak freshness. Most foods are good long after the sell-by date.
Fearing consumers will either not buy the food or think the stores are carrying old products, most grocery stores pull the items out of stock several days before the sell-by date.
http://www.businessinsider.com/why-grocery-stores-throw-out-so-much-food-2014-10
justeatit2016 