[vkou]

This is all well and good as long as Ethiopia can buy more food then it could have grown in those coffee fields.

Unfortunately, it also puts it at the mercy of forex rates, collapse of their monoculture, food shortages in other parts of the world causing rising food prices, any disruptions in foreign trade... Any of those things go south, and now you have millions of starving people. Sitting on a pile of coffee beans.

Why do you think the US government pushes billions of dollars into agriculture subsidies? Wouldn't it be so much cheaper if it just imported all of its food from abroad - where farmers get paid ~$1/day, instead of $6/hour.

There's a simple reason - it's because it doesn't want food riots, caused by some factor outside of their control. Nothing brings about regime change faster then the price of bread. [1] No well-ran country wants to be dependent on food, or oil imports.

Ironically, these same agriculture subsidies are what cripples agriculture in other nations - they can't always compete with Uncle Sam's subsidies.

[1] Just ask Mubarak. Or the Romanovs.