You never considered that there are different types of economic growth that generate different amounts of light, did you?

Dictatorships and Totalitarian regimes famously favor Heavy Industry over Light Industry, for instance. A boom in the steel industry does NOT lead to as much expansion in lighting as a boom in home construction and shopping malls to sell an expanded supply of consumer appliances.

This whole argument by the Economist is just plain nonsense, designed to advantage the types of economic growth favored in Western countries.