But they, and many of Africa's poorest countries, have something else in common: very young populations.
They are spread widely around the world but do share a number of similarities, notably young populations.
University cities such as Cambridge, Oxford, Bath and Bristol all have young populations that suit Pocket's business model.
Arab regimes, many of them U.S. allies, have lost touch with young populations.
Young populations without prospects found comfort in religion, some in the zealotry peddled by the likes of IS.
But firms are also fretting about generational issues in fast-growing emerging economies with young populations, such as India.
Slums may be poor, but they are economic powerhouses, with their mostly young populations finding innovative ways to generate income in an informal economy.
Referring to the Arab spring, Blair said it showed that young populations with radical forces operating within them were not going to accept authoritarian governments.
Poor countries with young populations, disorganized public health measures and substandard hospital care appear much more vulnerable than wealthier ones, the authors said.
Most of these places have large young populations that are moving from rural economies into cities, eager for cellphones and cars.
Some believe young populations could be driving everything from the Arab spring to China's economic miracle – and maybe the west's decline too.
