Aah OK.

Thought it might be a US specific issue.

Best I could find for NSW Australia is:

Gender and Incarceration

NSW’s prisons are gendered, with separate facilities for men and women.

COPP 3.8 uses a framework of “recognised transgender” people and “transgender” people. Those who have updated the gender marker on their birth certificate are “recognised” and must be treated according to identity documents. Those who have not legally affirmed their gender must still be received as their “identified gender,” but may be treated differently. For trans people with a binary or predominantly binary gender, the policy stipulates that you must be managed and supported as the “gender with which [you] identify at the time of incarceration,” even when you have been incarcerated previously with a different name or gender.

They are an incredibly efficient way, however, in the USA, to:

1. Have slave labour drive down wages for huge swaths of the economy.
2. Create a disenfranchised class by fine-tuning what constitutes a felony in many states. (In 10 states a felony conviction means never voting again without a pardon. Other states have descending levels of disenfranchisement.)
3. Put fear in the hearts of entire segments of the population as you apply your laws unevenly.

Remember the purpose of the system is not what they say it's for, but rather what it actually does.