I dont think there is anything to describe its just a fact that more people more income....for example in a family there are 4 people and only one of them is earning witb a salary of 10,000 so there are only 10,000 for expenditure of 4 people ..... but if two of them would be earning each of 10,000 salary then there will be 20,000 for the expenditure of 4 people. Hence More people more income.
