For starters the economic system is basically a ponzi scheme reliant on very high immigration to grow the economy (mostly through increased debt) but any talk of reducing immigration is seen as far right.Even though The Greens had a net zero migration policy until 1998 https://www.greenleft.org.au/content/greens-change-their-immigration-policy
The Greens state that immigration policy should be considered within the broader population policy. Their 1996 population policy had the goal of "stabilising" population numbers (hence the call for a reduction in immigration).
The Greens' new policy has a different goal: "An Australian population policy should consider the distribution of human settlements rather than just concentrate upon population size at the national level."
The changes are a significant shift to the left. The idea that population growth, in and of itself, causes environmental destruction has been dominant in Australia's environment movement. This led to the Greens', the Australian Conservation Foundation and parties such as the Australian Democrats lending their support to "a zero net migration policy" (where the numbers of people entering Australia can be no more than the number of those who leave) as propounded by Australians for an Ecologically Sustainable Population (AESP).
The problems of congestion, high house prices and huge competition for jobs are due in large part to the high immigration figures.