There were periods over recent decades in which protection was widely believed to promote the national economic interest in all six countries. The particular benefits believed to derive from protection varied from country to country and over time. A common explanation of tariffs is their role in raising revenue. At early stages of development characterised by low levels of per capita income and a relatively large resource or agricultural sector, it is sometimes cheaper administratively to raise government revenue through trade taxes rather than through income or expenditure taxes. The income distribution motive emerged in different ways in each country. For example, concern in Australia was to increase the population without causing a fall in the real wage and also to tax the rents of relatively rich landowners. In Australia, a component of the income distribution motive was to increase population and therefore the size of the work-force.