One thing to recognise here is that "income" isn't an entirely global concept, and has been pushed into a lot of places, which frequently go from something resembling a barter or trade economy into a place full of "low-income" people. Some people living on cents a day are living "fine" lives relative to their area, because not every exchange of goods or services is mediated by currency.
Here's their source. It seems like a pretty reasonable number.