Things like a flat tax have an illusion of fairness. There is the presumption that it could not be gamed. However, when one considers that it is predominantly supported either by those with wealth or those who think they will eventually come into wealth, I can only assume these people believe they will, indeed, be able to game such a system.
Even with the "regressive/progressive" (depending on one's point of view) tax system, many with wealth are actually paying a lower final tax rate than those without. This is primarily due to the greater options afforded them due to their wealth. So, it seems evident that those resources would afford those wealthy with similarly greater options for avoiding any flat tax.
My point is not to argue for or against a flat tax. (I imagine if we had had a flat tax all along, the same people who currently argue for said flatness would instead be arguing for a "progressive" tax, merely because it would be different and because, in this society, the wealthy always seem to actuallynced they deserve more and are being treated unfairly if they can't easily get more.) My point is to illuminate the fallacy of focusing on anything as "simple" as a choice in taxing systems as a solution to the inherent unfairness (perceived or imagined; to the poor or wealthy) in our society.
I believe the real solution is to (somehow) foster an ideology where people believe it is better to take care of others rather than to amass more wealth and power for themselves at all costs.
In researching the various healthcare systems around the world, I was struck by a common theme among wealthy countries which had universal healthcare: The wealthy believed it was in their own best interest to take care of the poor. Not as much because they were afraid of being overrun by hoards of thieving, poor people, but because they simply liked the idea of living in a country where no one had to do without healthcare.
My conjecture (which I have promulgated for a while) is that these other countries have (what I consider to be) a more "mature" attitude because they have had several more centuries to get used to their limited space and resources. Whereas this country has been spoiled by the perception of unlimited space and resources. The wealthy here still believe they can hide away, in their gated communities, with their private police forces to protect them from those hoards of thieving poor people. In fact, those wealthy (and those living with the illusion that they can become so, henceforth to be referred to collectively as "wealthites") often do not even have to be bothered to look at the poor. When they ARE forced to look at said poor, such as the beggars at the major intersections, the wealthites construct myths to console themselves. These myths say the poor choose to be so. Or that these beggars are actually making lots of money from said begging.
So, in conclusion, things like tax systems are mere window dressing. Merely rearranging deck chairs on the Titanic. Merely a wool that far too many willingly pull over their own eyes. The only true solution is to foster a society where people TRULY care about one another.
Love Care Think Do
I am working on filing for social security and medicare. Social security website allows you to do everything you need to EXCEPT make a check mark somewhere telling them to withhold taxes. I had to call a social security office to ask about withholding. I had to go to a different part of their site and download a form to fill out to tell them to withhold taxes and mail it in after searching google to get the nearest social security office to mail it to. If I had missed this little piece, I can imagine next year I would have been in for a shock when it was time to file and maybe had to pay penalties on top of that for not having enough withheld. 
