The reality, if the Wikipedia page can be trusted, seems quite a bit more complicated - many people and entities appear to be involved.
While searching for something else, though, this blogger came across this US patent application, which describes an "electronic purse" that seems suspiciously a lot like MPesa. The priority date is 2003. It's not exactly the same, but clearly people were thinking about this technology over a decade ago and at least three years before MPesa was launched.
Many people have said that MPesa was/is an example that supports software patents - had it been patented, the theory goes, it would be very easy to identify the true inventor and that person/entity would be making tons of money. This blogger believes the opposite is more accurate - had it been patented, there wouldn't be competitor services in Kenya (there are currently several), quality and service would suffer, and prices would be higher. Considering that a major reason for MPesa was to help the "unbanked", such a result would be quite unfortunate.
|Lion share (source here)|
Some would argue, however (and this blogger would probably agree), that even without patent protection, MPesa's lion-share of the industry effectively results in the negative outcomes mentioned above.