The current graduated system doesn't account for potential cost of living disparities. These are somewhat handled at the state level (NY State appears to allow roughly 28K income to be untaxed). A wealthy person could move to South Dakota and will pay less income tax (no state income tax) but for some reason no one's moving there.
Again you keep misrepresenting the article. More importantly this is about a series of articles (I've posted five so far) regarding how much the wealthy pay. I don't know if we'll see any shenanigans regarding local and state tax avoidance. They might not have the info.