An excellent point, and one I cannot entirely disagree with. However, even if that is good policy, the implementation still seems unsound to me. If I make $100k in TN and $10k in GA then my GA taxable income only goes up about $5k ($4545, actually), how does that accurately reflect your position? I am only being taxed as if I [would have] made about $25k in GA.

In short, GA DOR math:
$10k+$10k=$20k
$10k+$100k=$25k