The climate and farming land are a lot more favourable in the South/East. But in honesty like most people "discovering" land, they just happened to bump into the continent where they did and set up shop.

I don't know if the discovery and use of the Roaring Forties predates or postdates Australian settlement, but in the Age of Sail, you need to sail south of Cape of Good Hope, which puts you in a strong westward wind belt known as the Roaring Forties, which will spit you out on the southern coast of Australia, with the southeast being the easiest to reach (because it's the most southern one). So in terms of sailing time, it's easier to get to southern than northern Australia.

Historically sea and ocean navigation was coastal or as close to coasts as possible, plus influenced by winds and ocean currents. I imagine that going "straight" towards Perth was harder and less intuitive at the time that hopping near Asia and then through Indonesia and then over the Australian East Coast.

You may need to read more about Australian history, people were sent their from England if they committed a crime like stealing a silk handkerchief.

One example given below

https://en.m.wikipedia.org/wiki/Elizabeth_Thackery

It was a continent-sized jail ; you keep your baddest of asses as far from you as possible