The reason for mobile banking being explosive in growth is linked to network speed and availability. Mobile banking in countries I've visited are operated by the mobile networks. Therefore, they don't suffer from round-trip issues as bank apps. Plus ease of use. They have more in common with PayPal than normal banking services.
No datacenter because there is no communications.
But I've also read that mobile banking is MASSIVE in africa, more than the entire rest of the world combined.
Plus Africa is extremely diverse, I suspect there must be several cities that could benefit from a google datacenter.