It is a subsidy.
Are you one of the architects of common core math?
If this figure was $12,850 for "high-tax blue state" like New Jersey, or $13,800 for Connecticut, etc. -- even WITH the state/local tax deduction in place -- then how can you possibly claim that these states are being subsidized by "red" states like Alabama ($4,900), South Carolina ($4,700) or Mississippi ($3,900)?
What kind of math are YOU using?