As another Australian, can confirm. This year's tax return was as easy as logging into MyGov, verifying my contact details, confirming that the wage payments report from my employer was accurate, entering a previously-calculated number into the "capital gains" field, and pressing "submit". Took less than 10 minutes.

The only non-trivial bits are things like capital gains, work expenses, donations, but these are all things that you should be tracking in a spreadsheet as they occur through the year, and you'll have a number at the bottom of that spreadsheet that you can just copy over to your return (like I did with my capital gains, for example).

Even as a contractor in the past (keep in mind, in Australia, a contractor is a sole proprietor business), filing my return was as easy as copying income/expense totals from my invoice/receipt tracking spreadsheets into the return, adding any new depreciating assets to the list (that persists on their servers and gets recalculated each year) and submitting.

I don't have any interest accounts or private health insurance, but these would be some of the other things that get automatically pre-filled. And it's been this way for well over a decade now.