The 10% referred to in the article refers to state income tax. (Not all states have an income tax) That is on top of Federal Income tax. Federal Income tax started with a maximum rate of 7% on extreme incomes in 1913 and the maximum rate has oscillated between 91% and 28% since then, At present it is a maximum of 35% down from almost 40% in the late 1990s.
Then one also has estate taxes when you die.
By comparison Australia is probably somewhat more heavily taxed but only because the cutoffs for the various levels of tax are rather higher.
