There is so much confusion about tint shades. A smaller % means it is darker and the legal requirement in Victoria is no less than 35% for front doors and no less than 20% for rear doors and rear windshields.
People do choose darker shades than allowed legally, it is purely up to the customer if they’re willing to take the risk.
Again, the darker tint doesn’t mean it blocks the heat, better film type blocks up to 90% heat and you don’t even need a darker film to block heat.