I would approve of legislation and/or a Constitutional amendment to outlaw sales taxes, VAT, or any other form of regressive tax or revenue raising that leans most heavily on the poor rather than on the rich.
I don't ever expect anything like that, because too many people have a stake in raising money off the people least able to pay–and with the least political strength to object.
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Federal legislation would fail because it would violate the 10th Amendment (state's rights).
It's not going to happen as an amendment to the constitution because no state would agree to it. There have to be enough states to agree to a constitutional amendment for it to become part of the constitution.
Yes, it's a regressive tax.