Kiwis

The Freakonomics blog notes that you can buy a kiwi in New York City, imported from New Zealand, for 9 cents cheaper than the cost of sending a first class letter -- a non-perishable good -- from one side of NYC to the other.

The answer to this mystery, provided by an agricultural economist in rhyming verse, boils down to this:

For prices, though, it’s competition
Plus tariffs set by politicians,
That determines whether we see
Such delightfully cheap kiwi.

Another demonstration of the virtue of competition. I think the US Postal Service could use some.