By focusing on what people will lose out on his article (Test of Courage Sat 6th Feb) Peter Hartcher implies that as people move into a higher tax bracket they will be worse off. The maths doesn’t support that.
The statement that people could end up paying 50% more in income tax is open to pernicious misunderstanding. It is too easy for that to be misinterpreted by shock jocks, for example, to suggest that people will be paying 50% tax which is clearly not true.
A quick look at the ATO website yields the following mathematical truths for FY16.
If your Income is $37,000 Tax = $3572 Net income = $33428 (average tax rate 9.65% )
If your income is $80,000 Tax = $17547 Net Income = $62453 (average tax rate 21.93%)
If your income is $200,000 Tax = $63,547 Net Income = $136,543 (average tax rate 31.78%)
I imagine that someone earning $37,000 would be happy to trade places with someone earning $200,000. Even after paying $63,547 tax they'd be over $100,000 better off.