I agree with that sentiment, but the discussion is likely to come down to semantics more than anything else. At the end of the day it doesn't really matter if I earn $80,000 and pay 25% of my income in taxes, or if the IRS sends me a tax bill for $20,000 as a flat tax without any relationship to income. I would certainly support a true flat tax (i.e., everyone pays the same tax regardless of income, not the same tax rate) over any other alternative, largely for the reasons you cited.
I think it's much more simple than the reasons you cited, though. It makes sense to charge everyone a flat, uniform tax simply because the use of public assets doesn't vary depending on income.
I do not agree. Government has NO MORAL CLAIM on income, which is but an economic manifestation of labor. If one concedes that government has first claim on your labor, then you have conceded that slavery is morally acceptable.
So all that high-toned historical rhetoric about the Civil War is just so much hot air.
Of course, this won’t change in our lifetimes, but I think the concept of slavery = income taxes adds to the debate.