The function of the IRS is largely only necessary in a society that collects income taxes.
Systems such as apt-tax would render it meaningless largely to private systems, with only companies and corps having to deal with them.
And before I'm told that's undoable, the US had no income tax before 1913. When that was enacted, it was on the premise as relief to tariffs on goods and would only affect the superrich who would pay it and that it would max out on 1%. That proved a complete lie just 4 short years later, in WW1, when many more than the supperich had to pay rates far in excess of 1%.