Why isn't food priced according to its 'sell-by' date?

Tim Harford, in his "Dear Economist" column in the Financial Times, explored this interesting subject; his thoughts follow.

Dear Economist

Q. When purchasing perishable food items I look for those that have the longest "use by" date, even if I intend to consume them immediately. As a result I often bypass items that will be within their "use by" date when I intend consuming them, in preference for items with an even longer shelf life. Can I be accused of being wasteful by not purchasing items with the shortest acceptable shelf life, since I am increasing the likelihood that they remain unsold?

A. I hardly think the blame can be laid at your doorstep. The fault, instead, is with the unimaginatively static pricing on the part of the food retailers. They are presenting you with two different products at the same price, and you are simply choosing the better, fresher offering.

It is true that if you plan to eat the food immediately, the value you place on the fresher product might be lower than the value to someone who planned to buy it and leave it sitting around for a couple of weeks.

On the other hand, many people don't check the dates because they don't care. It would be a shame if they got the fresher product at your expense.

Ideally, then, retailers would adjust their prices to reflect the staleness of the food, with the price declining very slightly over time, before being slashed as the "use by" date approaches. Freshness fetishists like you would gladly pay more, while students, pensioners, and computer programmers would scoop up the cheapest products and scrape off the mold.

Products would be allocated efficiently according to preferences for freshness. It can only be a matter of time before the supermarkets catch on.