[goto11]

The purpose is to compare pricing across history. Food prices is a good yardstick since everybody throughout history need food. You cant really measure the price of "a night at an inn" for a culture without inns, for example. The cost of transportation is not that useful when most people walk everywhere.

[JoeAltmaier]

Well, you get the idea. Food is subject to very particular customs, environments and traditions. Much more so than other things. So likely a skewed measure. Got to be other things that make at least as much sense.