Historically, sugar was the predominant sweetener in Australia and it came from sugar cane as opposed to European sugar which is extracted from the sugar beet.
Sugar cane grew prolifically in the hot coastal areas of northern Australia and was an important industry, with huge sugar mills and major ports for transporting the stuff to cities as well as exporting it overseas.
Various sugars in Australia come from sugar cane grass, which is milled and refined to extract the sugar. Sugar cane is crushed in the mill and the resulting juice is purified and then boiled to produce a thick syrup. From this syrup, raw sugar crystals are extracted, usually via centrifuge, leaving a dark, sticky liquid called molasses behind.
If you've ever been to a fresh food market, you can watch a vendor feeding lengths of cut cane between two rotating drums that press and squeeze out the natural sweet juice it contains. With a few ice cubes, this makes a sweet pleasant juice on hot days – one can see how the ancient people would have noticed and desired the sugar from this sweet tall grass.