"Right now, a middle earner pays roughly a 15 percent payroll tax and a 28 percent income tax. That's a 43 percent tax rate"
First, 28 percent is the marginal rate and most middle income earners don't make that much money. I am married, making over 100K per year which puts me in the top 20% of income tax returns and I'm not in the 28 percent bracket. Even if someone does make that much more and fall into the bracket, they only pay the 28% on the high end of the income. Their effective rate is MUCH lower, especially if they have deductions.
My *effective* rate only cracks 10 percent in a bad year. Most families are already lower than 10 percent (if they pay income taxes at all) and a flat tax of 10 percent in the absence of a very high standard deduction would raise their taxes not lower them.