The 16th Amendment did not override the previous Supreme Court decision.
The 16th Amendment removed the founder's wise protection against direct taxation. The 16th Amendment removed the provision to levy taxes in proportion to the population.
Only for taxes derived from income from what ever source.
A tax on most income is and was an indirect tax, not affected by the constitutional restriction on direct taxes.
The money already accumulated by John D. Rockefeller et al would not have been ‘income’ either. It would have been accumulated. Money gained from interest on that accumulation could have been taxed as income, and should be.
A lot of people don’t understand the difference between direct and indirect taxes.
Direct tax is directly on you. An example is a poll tax, or a tax on property that you own.
An indirect tax is a tax on activity. Wages are derived from the activity of work. Per the 16th Amendment, taxes can be derived from income, from what ever source. This practically has the effect of treating all taxes on income as an indirect tax. Direct taxes, such as fines on property you already have, or money you already made, would be a direct tax.
I submit that one argument against Obamacare is its tax is not based on activity, and so must be apportionied by population.
That was not yet so argued, to my knowledge and belief. Since it was ruled constitutional ‘as a tax’ then it could be overturned by a mere majority of the Senate, not subject to filibuster, and it would be subject to the constitutional limitations on direct taxes.