Safaricom's mobile money transfer service M-Pesa is only five years old yet it has about twice as many subscribers as all the bank accounts in Kenya. The numbers are not growing as fast any more and many commercial banks now offer services that link to telco mobile money, or promote their own m-banking platforms, or extend services to customers through agents
But the attraction of mobile phone companies as preferred mobile money wallets is that they have gained customer trust with simple tariff structures. Millions of Kenyans are comfortable sending and receiving money by mobile phone. They know what it costs e.g. Kshs. 30 shillings ($0.40) to send money, and Kshs. 30 to withdraw money on the other end.
But for banks, they enter the mobile phone relationship with a stain in the minds of many of their customers as they have a legacy and history of imposing dozens of fees on their account holders & customers. While there are banks that have no ledger fees (just transaction charges similar to mobile phones Kshs 20 or 30 per transaction) and others that have free 'mobile' banking, the legacy of banks is also one of changing customer terms, raising tariffs and interest rates, phasing out services, migrating customers to new costlier services, phasing out services that were promoted as 'free', migrating their customers to more expensive options at will.
For comparison, if you leave Kshs 1,000 (~$12) in your M-Pesa account it will be there until you use it, with no phantom charges eating it away (it won't stay in your phone for 6 months). But if you leave the same Kshs 1,000 in your bank account for a few months, the money will be exhausted by various tariffs like ledger fees, dormant account fees, minimum balance fees and the account will be drained out and shut down. Unfortunately, a similar distrust extends to companies offering third party payment services m-commerce, payments, settlements etc. as they are new or unknown entities to customers until they establish a behaviour pattern with customer tariffs.
This should also be a caution to mobile operators not to shake up their cost structures too often. Safaricom recently changed their M-Pesa tariffs, but by having simple & clear disclosures and not levying hidden or unexplained charges, they will keep the trust that their customers have.