You said it yourself that the world is becoming a cashless society. Intuitively, there exist already many ways for people to trade electronically. All of them, however, require bank accounts. The problem with "dark africa" is that the people who live there are so poor beyond your imagination. They have so little that bank accounts are impractical to them. Even Meir mention how a lot of people don't even have bank accounts in one of his podcast interview.