Yes It is indeed illegal in NSW to have no roof lining, Mrs got pulled over due to the lining just let go on her way home from work one night, and said fix it, She asked if she could just remove it but apparently its a fixture to the car and must be in place, and that the old foam can fall into your eyes etc lol, and was told if its not fixed the car will be defected. So i just ripped the roof out and re-stapled & Glued the same piece back on. She was then pulled over again and said good to see it was fixed.