"One analysis of tax burdens relative to income suggests that in ten US states the percentage of income spent on taxes by low-income people is six times greater

"One analysis of tax burdens relative to income suggests that in ten US states the percentage of income spent on taxes by low-income people is six times greater than that paid by the wealthy" The footnote is to a study at https://itep.org/whopays/ https://itep.org/whopays/ - is this a reputable study? If so the findings seem like something people should be objecting to in the strongest terms possible - I'd be horrified if it were true in Australia. But at the highest level it seems to contradict the usual numbers you see floated around where the wealthiest X% pay Y% of all taxes (where X is considerably less than Y).