Alaska, Florida, South Dakota, Washington, Nevada, Wyoming - none of these states have state income taxes either.
New Hampshire and Tennessee limit it to dividends and interest income.
I live in Florida, the tax structure here is regressive because it focuses on sales taxes, but my incentives seem a bit better than when I lived in Philadelphia and my income got taxed by the city, state, and federal government. I really have no idea where it went either, as the streets were filled with potholes and most of the sidewalks were covered with ice all winter long.