And yet this works fine outside the US.
This happens across the US political specturm, whether about their tax system, banking system, gun reform, electoral reform, and many other issues; it's a frequent refrain that the US is so different it can't learn from others.
As a US citizen who is resident elsewhere it is infuriating to watch.
Alternatively, it's a frequent refrain that the U.S. _should_ learn from others, which is e.g. why we should preserve our federal system, electoral system and rights.
I think it's a _good_ thing that the several states are separate sovereigns from the United States, and I think it's a good thing that the states are entirely reliant on the United States for their budgets (and in fact, those places where they are reliant, e.g. the highway budget, have led to anti-federal things like a uniform drinking age, something which is 100% not the business of the United States government).
If the United States looks only inwards, however, there's nobody left to learn from in terms of how to run a Union, since there is only one United States, and its powers and responsibilities are (because of federalism) quite different from those of the states.
It shifts the blame from the current politics which is something people can engage with to "reasons out of anyone's control", which just helps maintain status quo.
Most of the times it comes down to constitutional issues in which case they are technically not possible.
Case in hand; the federal government has no constitutional right to prevent the states from collecting taxes -- which would be required for there to be one official Collector of Taxes for all the states.