"Thus, once they lost the currency exchange mechanism, which had institutionalized their political strength, multinational corporations found that they could not operate in the particular type of political arena that developed in West Africa after independence. These companies then coped as best they could with the overvalued exchange rate and looked to invest their money elsewhere, where there were more favorable economic circumstances and politics. Pace dependence theory and the literature on globalization, the problem of developing countries, at least in the area of exchange rates, is not that multinational enterprises have been too politically powerful but that they have not been strong enough to influence policy."
From Jeffry Herbst, States and Power in Africa: Lessons in Authority and Control, pp, 219.
This is definitely my favorite book on post-colonial state building.
This is not to deny the historical causes of underdevelopment in Africa, the main one which is the abject weakness of many African states (in terms of basic state functions: protection/contract enforcement). But it is to say that, in the context of state weakness, some pretty terrible policy choices were made by new leaders. It was not the presence of commerce and trade, but rather the barriers to economic activity, which largely explain why Africa remains so poor.