The conditions were ripe

In Kenya many people work in the city and periodically send money home to family in rural villages. They first visit a shopkeeper in Nairobi and deposit cash in exchange for virtual currency in their M-Pesa account. This is sent by mobile phone to a family member, who then withdraws it for cash as needed. This is incredibly advanced given that basic infrastructure like water and power is severely underdeveloped. There are essentially two reasons why M-Pesa succeeded.

  1. Everyone could use it instantly
  2. It was far cheaper and safer than the existing solution

It was instantly usable because it piggybacked on top of the existing Safaricom network of cellular towers and salespeople. 70% of Kenyans have phones and Safaricom has a greater than 98% market share, which means essentially everyone could use M-Pesa. 

It was far cheaper because paying a 7% transfer fee on 500 shillings much better than paying 200 shillings to take the bus to accept the payment. And far safer because your money is secure even if your phone is stolen (thanks to a PIN). Theft frequently occurs, so this is important.

Similar solutions are struggling to gain traction in other East African countries such as Uganda, which have a similar need for familial money transfers but don't have the carrier monopoly. Being cheap and safe wasn't enough. Distribution was key.