I have noted previously that one of the key reasons why Australia’s high population growth (immigration) is lowering the living standards of existing residents is because of the strain that it places on infrastructure, which inevitably leads to more congestion on roads, public transport, as well as more expensive housing.
Basic math (and commonsense) suggests that if you double the nation’s population, you need to at least double the stock of infrastructure to ensure that living standards are not eroded (other things equal).
