The idea that "Americans hate taxes" has become a truism without the benefit of being true. Instead, Americans see paying taxes as a civic obligation and a political act. To be a taxpayer, Americans believe, is something to be proud of. It is evidence that one is a responsible, contributing, and upstanding member of society, a person worthy of respect in the community and representation in the government.
Because taxpaying is seen as an emblem of civic worthiness, denying the poor the status of taxpayers has the effect of denying their political standing. Classing a large percentage of the populace as a kind of second-class citizenry is genuinely toxic for democratic norms.