Unfortunately the ship has almost sailed in Africa, most countries use mobile phones for payments, but the market was wide open until just recently. They still paid in goats(to stay in tune with your approach) not so long ago.
That 'most countries are using mobile phones for payment' is hardly a missed opportunity. If they are using litecoin... then yes, I'll agree, but they are using local, proprietary systems. It's still a massive opportunity for many reasons. With bitcoin they can pay for things globally, and in turn receive remittances instantly. Keep in most of them don't have bank accounts. Also, the political systems their are in pretty bad shape. The managing of their currencies might even be worse than the USD. Finally, to your point, they are already comfortable with digital, phone based currency. Provide them with a vastly superior e-currency and you don't think they will go for it?
Edited to fix bad quote format