Doesn't the word "power" describe congressional authority better than "right" or "service?"I'd consider none of those "rights". Post offices and minting money are legitimate (constitutionally authorized) services of the federal government. Education is not.
"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..."
Transcript of the Constitution of the United States - Official Text