The Constitution requires that per capita taxes, not tariffs, be uniform.
Who's Constitution you looking at?:
A per capita tax was a tax laid in proportion to the census(i.e. population) of each state.
Per capita taxes are Capitation & Direct taxes only
A LAW DICTIONARY
by John Bouvier, Revised Sixth Edition, 1856:
CAPITATION. A poll tax; an imposition which is yearly laid on each person according to his estate and ability. 2. The Constitution of the United States provides that "no capitation, or other direct tax, shall be laid, unless in proportion to the census, or enumeration, therein before directed to be taken." Art. 1, s. 9, n. 4. See 3 Dall. 171; 5 Wheat. 317.
Hylton v. United States(1796), 3 U.S. 171
"A general power is given to Congress, to lay and collect taxes, of every kind or nature, without any restraint, except only on exports; but two rules are prescribed for their government, namely, uniformity and apportionment: Three kinds of taxes, to wit, duties, imposts, and excises by the first rule, and capitation, or other direct taxes, by the second rule. " "the present Constitution was particularly intended to affect individuals, and not states, except in particular cases specified: And this is the leading distinction between the articles of Confederation and the present Constitution." "Uniformity is an instant operation on individuals, without the intervention of assessments, or any regard to states," "[T]he DIRECT TAXES contemplated by the Constitution, are only two, to wit, A CAPITATION OR POLL TAX, simply, without regard to property, profession, or any other circumstance; and a tax on LAND."
Tariffs on the other hand is a short hand reference to a "tariff of duties" (i.e. tariff) Duties must be uniform throught the United States. Meaning the same taxe law applicable without regard to states or one's location in the United States.
A LAW DICTIONARY
by John Bouvier, Revised Sixth Edition, 1856:
TARIFF. Customs, duties, toll. or tribute payable upon merchandise to the general government is called tariff; the rate of customs, &c. also bears this name and the list of articles liable to duties is also called the tariff. 2. For the tariff of duties imposed on the importation of foreign merchandise into the United States.
Constitution, Article I Section. 8:
The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States; but all Duties, Imposts and Excises shall be uniform throughout the United States;