Many people have no idea how our taxation system works. I've talked to people who vote democrat but aren't very interested in economics & economic politics and they have told me they think a flat tax is a good system.
I like the idea of a flat tax with minimal deductions or a two tiered tax system with minimal deductions (ie 10% & 20% federal tax + all other taxes). Near 50% of people don't pay federal taxes because they use deductions, don't report income or qualify for exemptions. We waste so much money on accountants.
When politicians argue about federal tax rates, many people realize we pay so much more in total taxation. Our corporate tax rate is the highest in the world now, that needs to be reduced ASAP.