I don't think taxing production (earnings, labor etc.) is the right approach at all, be it flat, progressive, regressive or otherwise. I think eliminating ALL income taxes at all levels for all persons and entities is the way to go (which of course also means the elimination of the IRS), and replace that system with a simple sales tax (on consumption). Prices of all goods would fall substantially since it would no longer be necessary to build in the cost of excessive income taxation; hundreds of billions of dollars would be unleashed that is now tied to complying with our failed system; and a 15% or so tax on purchased goods would be met with satisfaction as the people would be retaining nearly all of their paycheck.

But it will probably never happen because of the GREED of GOVERNMENT. A government that does nothing but continue to grow and encroach on YOUR liberty.