The amount of lost time and productivity due to dealing with income taxes nationwide is insanely high.
The number of accountants, lawyers, and auditors that work full time on it, plus the percent of time that small business owners and individual taxpayers have to dedicate to it each year, costs an uncountable total number of lost hours per year. And just as bad, it requires a ubiquitous massive surveillance apparatus on all sorts of income to enforce itself.
No taxes are enjoyable, but income taxes are really the most counter-productive and onerous ones. Taxes on properties, imports, and retail sales have so much of a lighter touch to track and collect than income taxes.