Not neccessarilly. They talk of purchasing power, but competition is also a factor (naturally), which can result in lower prices from better served, richer centers to worse served, poorer areas than vice versa. Especially this assymetry can be true of leisure routes - if you want to fly from Munich to somewhere warm, you can choose from any number of destnations in Spain, Italy, Croatia etc., but if you want to fly out of Dubrovnik to Munich or further on (and not on a lowcost carrier), you don't have that much choice, especially out of season.