Based on the US Government's official legal websites, no law requires 99% of Americans to file and pay Income Tax.
The 16th Amendment to the Constitution of the United States: “The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration.” So, uh, WRONG. I’m guessing that’s somewhere on the “US official legal website” lol.
But also, nobody ever said 99% of Americans are required to pay income tax. To be required to pay income tax, you have to actually make some income. I’ve had a few years when I wasn’t working, so, no tax returns for me then, lol.