We’ve actually got an even bigger private prison issue than the US by proportion.

Nearly 40 per cent of Victoria’s prisoner population is housed in three privately managed prisons – Port Philip Prison, Ravenhall Correctional Centre and Fulham Correctional Centre. As a consequence, Victoria has the largest proportion of privately managed prisoners in Australia, while Australia has the largest proportion in the world.

https://lens.monash.edu/@politics-society/2019/06/28/1375605/victorias-prison-system-rising-costs-and-population-little-accountability

The lobby doesn’t have quite the same financial clout just on population size but it’s a significant factor in Australia’s modern handling of the issue.