The markets, supermarkets and shops all form a part of the informal sector and considering the size of Nigeria's population should provide a lot of employment and enterpreneurial opportunities for the populace. Another point that i deduced from your post is that this has happened inspite of the poor infrastructure that exists in Nigeria. For greater accountability to yield better leadership, appropriate systems should be in place (e.g. judicial, law enforcement, accounting etc) and this will only happen via a sustained drive for reform. I believe that continued support for reform and the people who drive them by international agencies (e.g. the World bank) can help the process. We must not neglect the "marriage" between politics and the economy, and the challenge i find here is that redirecting the focus from oil to non-oil will require a long-term strategic thinking which the average politician doesnt care about (as he/she is focused on the next 4 years). It will also require implementation of the ideas/policies/ programmes by government staff which may not have the capapcity to do so.