“This, and the ability the income tax gives to violate the privacy of citizens and intimidate enemies, is why the government loves the income tax.”
These issues are not intrinsic to an income tax. Suppose there were a 10% flat income tax, withheld by employers and financial institutions. The employer could simply report his total payroll costs and send the IRS a check for 10% of that total. The IRS wouldn’t need to even know who the employees were. Financial institutions would total the gains made by all their investors for the period, and send the IRS 10% of it. The IRS wouldn’t need to know who the investors were. Still an income tax. Still withheld at the source. No individual reporting. No IRS audits of individuals. No information available to base handing out credits, exemptions, and deductions (tax welfare) through the tax code. No political favors to be handed out to groups of taxpayers.
There is no reason why the same mistakes would have to be repeated if we reset the income tax to a flat 10% rate collected at the source so no personal information could fuel the deduction/exemption/credits political machine.
I am not opposed to a flat tax. As a practical matter it would be an improvement. Nevertheless, you overlook the fact that millions of people are self-employed, that not income is wages, etc.