Just as an afterthought to this thread; the subject of global recognition of facilities was on the agenda at an EASA Conference in Cologne earlier this week.
Essentially, it's all about EASA negotiating Bilateral agreements ("BASA"s) with other administrations, eg USA, Canada, Brazil, China and so on, for mutual recognition of each side's approved organisations and licences. This has been going on for a while, starting with N. America, but is obviously a slow process.
I suspect that Nigeria might be some way down EASA's list of priorities, but perhaps I'm wrong. The level of mutual confidence might need to be nudged upwards a notch or two before an agreement can be concluded.
And then there's all those nice freebies for "inspections"; we wouldn't want to lose those, would we?