bkmk
Additional point not mentioned - most national corporations are headquartered in blue states, so their federal taxes are recorded as coming from there, in spite of the fact that their profits come from national operations.
Ditto for the “owner class” of these corporations, as the wealthy also disproportionately reside in blue states. Their incomes also derive from the national scope of their assets, such as their holdings in equity and debt, directly or via mutual funds, hedge funds, etc. But their income taxes are registered in their residential addresses.
A national split would require split tax filings for all these corporations, requiring reporting of income derived in each new country. And ditto for holders of these assets, directly or indirectly.