Can mesh networks be the saving grace for the next billion users?

For some time now, i've been pondering the idea of how developing countries can use mesh networks to build smarter cities and get the next billion users connected to the internet. Smartphone are now becoming more readily available in developing countries and could be the most cost effective way to build networks of connected devices. This could have massive economic growth potentials for developing nations. Why is this not something that is explored more? Like all things, I understands there are technological limitations and possibly areas of security concerns, but I am missing something crucial here?