A question that everyone saying "this is so cool, why don't they do that here" should be asking is why so many people find this option necessary? The core reason is that the banks in Kenya suck. Period. (Okay, I was only there for two weeks but three trips to banks in that time period were more than I would wish on just about anyone...) They make US cable companies and telcos look like paragons of good service and low friction transactions.
In a country where there are not ATMs on every corner, credit card swipers in even the most insignificant bodega, and where you stand in line for an hour to get the cash you will need for a week or month's worth of purchases any system that reduces transaction friction (especially for small-scale purchases) is going to be a win. In places where the economic transaction infrastructure has already pushed down the cost of doing business the appeal of such a system becomes one of convenience rather than necessity.
I used prepaid sims from MTN and SafariCom when I visited Kenya and east Africa this summer. 50 cent activation fee and $5.00 for all the minutes I needed (including to the US) for 3 weeks on a network that seemed as reliable as my at&t service. Humiliates American carriers in terms of value.
People from literally all walks of life use cell phones like this. From the Masai herdsmen in Tanzania to the dirt dwelling inhabitants of the Kibera slum in Nairobi. Here's a mobile shop in the heart of that slum: http://www.flickr.com/photos/petermarks/4017875315/in/set-72...
I suspect you can get away with things like these in Kenya because the state is weak and cannot enforce regulation in the banking sphere, i.e. demand banking licenses and proper accounting from phone companies.
Allowing for easy money transfer between cell phones leaves less control for the state and opens up opportunities for financing illegal activities and money laundering. From egoistical or anarchistic point of view it would be cool, but one can clearly see why it isn't allowed in many other countries.
In Russia banking system also sucks (though not so badly) and usage of banking services by the general population is low. So is quite widespread to pay small amounts, like for paid web services, with SMS, or to repay small personal debts by topping person's cell phone (prepaid system is prevalent). But phone to phone transfers are not allowed. And if you wish to receive payment for your online game via SMS, operators take commission of 30% to 50%. Is it that bad in other countries as well?
Overly strict regulators are actually one of the main reasons that banks in developing countries can be such a PITA.
Most of these countries in Africa with mobile payment providers have spent a lot of time with banking regulators getting these systems approved and they have received a lot of praise by people in the payment industry for doing so.
You idea that easy money transfer allows less control for the state seems to me to be misplaced. This fear of the money laundering is a huge problem in the US and Europe and is stifling innovation.
Most people in Africa work in the informal sector, so yes by OECD standards just sending money they illegally made selling Yam at the market back home would in theory be money laundering.
However there is pretty good anecdotal evidence that M-Pesa in Kenya is really helping develop the economy from the bottom up.
Shame is the right word here, as this is exactly what I feel every time I hear about another country adopting some convenient mobile payment method, from cell payments to mobile walletc, etc .
Why are we so behind? Imagine the opportunities? And then I realize what a drag on progress our parasitic banking system has become.
In a country where there are not ATMs on every corner, credit card swipers in even the most insignificant bodega, and where you stand in line for an hour to get the cash you will need for a week or month's worth of purchases any system that reduces transaction friction (especially for small-scale purchases) is going to be a win. In places where the economic transaction infrastructure has already pushed down the cost of doing business the appeal of such a system becomes one of convenience rather than necessity.