Why is every country in Africa like an island?

Africa has 54 countries, each country has its own currency with different value, different regulation, different rules, most different languages and even different payment especially when it comes to mobile money.

Picture this Mpesa in Kenya is from Safaricom while Mpesa in Tanzania is from Vodacom and they don't even talk to each other or share data & information the only way these could communicate and transact with each other is by doing an integration btn these 2 companies and do international transfer or remittance! and there's no infrastructure service for business to run on (eg, APIs that allows business in Kenya getting paid by a customer is Tanzania or from Tanzania merchant being paid by a Kenyan customer, even the Lipa number of Mpesa vodacom vs PayBill of Mpesa Safaricom can't receive crossborder payment)