It's really an insulator, to stop the knob from freezing you hand in colder climates, not really likely to be an issue for you in QLD, down here in VIC the knob can get pretty bloody cold on a winters morning, so I can only imagine how bad it would get in a really cold climate.
On the other hand in your hot climate the alloy knob would probably burn the buggery out of your hand on a hot day in the sun, the knob gets pretty hot here where the weather is milder. So if your knob gets too hot to touch then one of these wooly covers would insulsate the hot knob from your hand.