Don't countries like ethopia skim the foreign currency sales of things like coffee in various ways (ie, low official exchange rate, then elites can resell at higher black market rate and give farmers the less valuable local currency).

This is a common issue in a lot of developing countries - and also makes investment harder because it can be very difficult to get your foreign currency profits out (elites only want to buy at fake low rate - if they had to sell at it they'd lose their profit).