What exactly do you have against a progressive tax?
Unequal treatment under law by government...
Sales tax, is not unequal treatment, discriminatory, nor based on some bullshit subjective concept of fairness... 5% (or whatever rate) on every dollar spent in the sale of an item to the consumer... whether you make 500K or 15K... whether you spend $500 or $5... it is not about the person, it is about the dollar(s) spent...
Income tax should be just as blind... and about the dollar earned, not the person, not the boo hoo sob story, not about the buying of votes...
It is not equal treatment to have one person paying 0% or 5% when another is paying 28%... it is not equal treatment either to have specifically designed loopholes for certain groups of people...
Hence.. for true equality in treatment by government under law.. eliminate the progressive code and eliminate the deductions and loopholes... and with the simplification you don't need as huge of a government entity to collect and analyze taxes... and with everyone having a stake in the game (the same stake in % of every dollar), IMHO you would have more public scrutiny over how government spends and does its job