The USA has "deductions", which are convoluted rat races where everyone does a bunch of paperwork so they all get a small discount which is cancelled out by higher overall rates. The IRS can't tell you which deductions to take, since they don't know your whole life situation.
It's the same structure that makes you pay 3% extra for everything you but so you can get 1-2% back as a credit card refund, and makes you get a supermarket loyalty card, and frequent flier miles, etc.
Australia has "deductions" and the filing forms are plenty complicated, doesn't stop them making a nice website with a free e-filing system.
For pretty much everything is prefilled, and you just double check from your own records, fill in the various deduction screens for whatever class of deductions you're claiming.
It's the same structure that makes you pay 3% extra for everything you but so you can get 1-2% back as a credit card refund, and makes you get a supermarket loyalty card, and frequent flier miles, etc.