In all States and Territories of Australia, the darkest legal window tint permitted on a vehicle is one with a VLT (visible light transmission) level of 35%, on all vehicle windows (excluding the front windscreen, which is not allowed to have any window tint with the exception of the visor strip across the top). The northern Territory and Western Australia are the only exceptions. In the NT you are allowed a minimum VLT of 15% for windows behind the driver; and in WA you are allowed 20% VLT on windows behind the driver.
So what's problem? What people don't realise is that most vehicles already have a slight factory installed tint in the glass.