FACT #1: Wages were taxable before the 16th Amendment because SCOTUS held in 1881 that a tax on wages was not a direct tax.
OMG, just stop with that old tired nonsense! Springer was an attorney and bondholder who reported $50,798 in income back then.
The issue in Springer was again "income, gains, and profits" during the year 1865. $50,798 with factoring in today's inflation is over $1.5 million. Ergo, Springer was not a laborer, craftsman, or farmer, or such anything.
Pollock modified the findings of Springer; and the (since overruled) Hilton case was nothing other than a silly ass argument over taxes being levied upon horse buggies without apportionment--it has no bearing in modern society, period.
The Revenue Act of 1864 unequivocally stated: "Section 116 of the Act imposed the tax on "the
gains, profits, and income of every person residing in the United States, or of any citizen of the United States residing abroad, whether
derived from any kind of property, rents, interest, dividends, or salaries, or from any profession, trade, employment, or vocation, carried on in the United States or elsewhere,
or from any other source whatever" and raised its tax rates from the 1862 Act that started out at 3% over $800 (which is now the equivalent of more than $24,000) to 5% above $600 (which is over $18,000 in today's dollars.)
* Notice the similarities between the above and the 16th Amend., i.e., "gains, profits, and income ... derived from any kind" and "from any other source whatever" versus "the power to lay and collect taxes on incomes from whatever source derived," hence, properly as an indirect tax it's not being 'directly' imposed upon whatever the source might be, but 'indirectly' upon only the 'gains or profits' as "incomes," being derived from whatever the sources may be. The distinction here is whether or not a positive financial severing had occurred throughout a given tax-year.
The 16th Amend., was always, clearly, and only intended to impose an indirect tax upon realized wealth and gain, i.e., a tax upon the wealthy and privileged, it was never thought of as a workers tax or super-tax until after the 'stoppage at the source' withholding scheme began in 1943 and the socialist government bureaucrats of the time realized that they could get not only away with keeping the money being voluntarily contributed by the national workforce (being supportive to war efforts), but they could in addition impose all sorts of machinations to tax this, to exempt that, to deduct the other, or to cunningly convolute, subjugate, erode, and obfuscate the U.S. Constitution.
Being compensated for one's labor or personal ability is an equally contracted (quid pro quo) exchange and falls within both an individual's freedom of association and their right to freely contract outside of governmental interference and molestation (e.g., 14th Amend., Lochner v. New York, 198 U.S. 45 (1905).) Viz., working 80-hours in exchange for $4,000 in a skilled occupation is not comparable to one paying their employees $4,000 bi-weekly while maintaining a realistic expectation of grossing $25,000 during that same period of time.
In Pollock, the point had been made unarguably and succinctly clear that the imposition of any indirect taxes upon associative objects, while still relational to its source must be treated as if its a 'direct tax' upon that source else face voidness under unconstitutionality. So, hence, even though you may teach a cat to bark, it's however, still a cat.
It's so nice that y'all never lend consideration to the pointedly stated "or other direct, tax" within A.I,S.9.,C.4: "No capitation, or other direct, tax shall be laid, unless in proportion to the census or enumeration herein before directed to be taken." The Court was either purposefully or negligently incorrect on their assertions with respect to direct taxes as there are others, e.g., personalty taxes. Regardless, this point was exhaustively debated throughout the Federalist Papers and was well within the minds of the Legislature during Congressional testimony for the ratification of the 16th. Amendment.