Income can be earned not only by being a workman, like a plumber, but also by forfeiting the use of one's own money for a time period and we are paid interest for this by lending or investing in a venture offered on the stock market, for example, or by offering a service like cleaning, hairdressing, building, etc. and rent if we have a house let out to someone. People want these services and will thus be prepared to pay for them. Thus it is both goods and services which comprise the Gross Domestic Product of our economy.
Demand determines what is supplied within a free enterprise economy/capitalist economy such as that of Australia's.
However, it is not 100% free enterprise economy. There are some government regulations, eg recently threatened caps on gas/electricity prices being charged are being touted by government as possible ways of preventing the extremely high growth in what is being charged customers of private energy suppliers.
There has never been an across-the-board restriction placed on individual consumer expenditure based on age and assets, thus (aged pension access) nor will this ever happen. To monitor this would be an exorbitantly expensive excerise of enormous magnitude, throwing up all kinds of anomalies, and unfair outcomes. The market is the mechanism which determines what is and how much is produced. This was identified and understood in Adam Smith's famous Wealth of Nations treatise which describes in details how capitalism works with minimal direction from dictators ir gonernments.
Western economies are democratic and market forces predominate. Thank goodness for that.
