Government subsidies in an attempt to alleviate poverty and to increase access to energy.
- http://en.wikipedia.org/wiki/Electricity_pricing#Global_electricity_price_comparison
It isn't just developing nations that subsidize electricity. Here in California, for instance, there are consumption tiers. So the person that has a large family and consumes four times as much electricity as someone a few blocks over who lives alone can pay marginal rates nearly three times higher (e.g., $0.12 per kWh for the first tier, then $0.20 for the next, then as much as $0.30 per kWh). The person that consumes little electricity never exceeded the first tier of consumption and thus never pays more than $0.12 per kWh.
But in the developing nations, subsidies are often used to offset the cost of electrical generation and distribution. Many of these same nations also subsidize fuel costs.
What these subsidies tend to do though is cause wasteful consumption. If you electricity is under $0.02 per kWh, you might do something like use inefficient lighting always leave the lights on (when the power isn't in a blackout).
But if you can mine with these subsidies (and your neighbors don't wonder why you leave the windows open even in the winter), more power to you (pun intended).
I've seen people claim to receive free power, other then that. Where I live in the US seems to have the cheapest power. I'm sure there are places I don't know of, but we are definitely capable of the same rates.