Low-income Americans are undertaxed

I have noticed a not-at-all subtle shift in the tone of conservative movement rhetoric in America, that (in terms of conservative sources I'm tuned in to) has seemingly unfolded in just the last few months. Since the Reagan revolution, the tendency of movement conservatism has been a zero-tolerance policy toward tax increases on any subset of the population, period. Now the meme being parroted by grass-roots conservatives (I'm willing to assume they're not all sock puppets) is that citizens below about the 40th percentile in income are undertaxed, the talking point being that they "don't pay any income tax." I initially interpreted "40% pay no income tax" as code for "I'm against the Earned Income Credit." But it also appears to be a salvo in the far-right's age-old struggle to replace the income tax entirely with sales tax (code phrases "fair tax" [sic] and more recently "consumption tax").

According to Bill Carver, "Most democrats don't like a sales tax because it gives up conrol and doesn't punish the rich." Disregarding the 'punish the rich' rhetoric, the 'control' issue is an interesting frame to put on the issue. People control the amount of sales tax they pay by controlling the amount of taxable consumer goodies they purchase. Sounds fair enough. But how is income tax similarly not under individual control? I can't count the number of times I've been lectured by libertarians and other conservatives about my relationship with my boss being 'voluntary,' let alone how many times I've heard the cliché "nobody's holding a gun to your head." While economic competition provides resistance to any attempt to increase one's income (and hence one's income tax liability) there is no resistance, let alone coercion, standing in the way of decreasing one's income. One (who itemizes deductions, anyway) can even decrease one's taxable income without any change in earnings through philanthropic giving. Of course, all taxation is coercion, and justifying taxation requires coercion to be a means justified by some end, one of the more popular being the maintenance of civilization itself. It is not my purpose here to debate the legitimacy of taxation in general. I simply don't see how sales tax is under a taxpayer's control in ways that income tax is not.