> I'd be willing to bet that if you adjusted the brackets for cost of living, CA is taxing the poor more than those other states are.

Why bet when you could actually look up the figures yourself? California has a very progressive income tax with more brackets (ten) than other states, starting at 1% for the lowest bracket. Meanwhile North Carolina charges a flat 5.75% and Wisconsin's lowest income tax bracket is 4%.

Because a cursory lookup doesn't tell you much. Taxes are much more nuanced than a tax table. There are studies showing that a flat tax without loopholes or special deductions is a higher effective rate for the wealthy than a "higher" marginal rate in a progressive system. Additionally, states vary in what is deductible or non-taxable income.