Right. He's basically complaining that certain individual taxes (like sales tax) serve to mitigate the progressive nature of income tax, making the net result

Right. He's basically complaining that certain individual taxes (like sales tax) serve to mitigate the progressive nature of income tax, making the net result still progressive but not as steep as he wants. That is a fair position to argue, but not really a new contribution to the discussion (this makes it off-topic for HN.) An analysis of corporate taxes and regulations, and how they are passed on to consumers, would be a genuinely new contribution. This would be especially interesting if feedback effects were included -- paying sales tax on something with an inflated price due to other taxes, for example. We have a government that specializes in taxes (and fees and regulatory costs) that are hidden from the consumer; it would be a great contribution to show which subset of consumers actually ends up paying those.