Tithing- The 10% Principle

So I was considering social justice recently, and welfare and government programs and the like, and it occurred to me to wonder, why did God set tithing at 10%? Well, that question I don't think I can safely or sufficiently answer, but it did bring to mind a question of how we might more efficiently manage the poverty issues of the United States.
See, mathematically speaking if 10 working individuals- variously supporting families or themselves (although the point is irrelevant here)- contribute 10% of their income to the church, then the church has received altogether a sum equal to the average wage of those 10 individuals. Moving along then, if for every 10 working individuals there is 1 incapable of working (again, regardless of family situation) then one might suppose that the church could give to that individual the sum equal to the average wage of the 10 working individuals.
But wait, you say- how will the church pay for its mortgage and maintenance? Well, I am of course supposing that the 11th individual, having received an average wage, will tithe his 10% back to the church.
It is therefore safe to say that 10 individuals, providing an average wage to an 11th individual worthy of it, will not only have safeguarded the 11th man for a year, but will leave the church with a full 10% of the average wage.
A visual of the math with random wages is as follows:
(in thousands) 30+40+45+50+35+55+80+25+50+45 = 455 (total wage)
455 / 10 = 45.5 or $45,500 (average wage)
$45,500-$4,550 (amount given to the 11th individual, minus tithe)
Therefore, 10 working individuals will support 1 man as well as, presupposing a humble church, building, perhaps one sixth to one third of the church's expenses for the year.
One might therefore suppose that according to this principle, a church with 50 working individuals may support up to 5 individuals while contributing (using earlier numbers) $22750 to the church.
Now of course one may assume that one of those individuals to be supported is the minister, so that leaves the equivalent of average wages for 4 more people. Presuming that in a church there might not be 4 individuals in need of that much income, the church building itself may be much sooner paid off.
This isn't even getting into the growth factors of families with many children who then begin working at a young age and tithing, increasing the income of the church. However, if we suppose that in a church of 400 people (as an artificial maximum) there might be 40 working fathers representing average families of 5 people (so 200 people, including wives who would stay at home), then that church would be able to provide the equivalent of a full average wage to 3 individuals/families beyond the minister.
Of course, one may note, the average wage in many if not most churches will exceed the poverty line established by the federal government, and so one might presume then that churches need not in fact provide the total of an average wage to anyone besides the minister whose job is in the church. This opens up the possibility that 40 working individuals can provide for more than 3 people who are facing hard times.
There are a wide number of factors that I am not even taking into account, such as the potential incomes of widows/widowers, wives, and bachelorettes (not a word?). The basic principal, however, seems to indicate that a church is able to provide for somewhere between 9% and, say, 20% of its population, based solely on tithing.
Coincidentally, according to 2004 statistics provided by CIA.Gov's world factbook, individuals in the United States living below the poverty line comprised 12% of the total population. Presuming (rather optimistically) that the poverty line represents the level at which basic subsistence ability begins to fail, 12% of the population is in dire need of a hike in income.
According to such a principle, then, presuming that the entire 12% does not in any way reflect those in prisons, those who should be in mental institutions, and those who simply refuse to work for lack of responsibility, it is reasonable to expect that, should the whole population of working individuals in the U.S. whose average GDP sits at approximately $47,500 should be sufficiently capable of handling that 12% of individuals quite handily according to the 10% principle.
Politically speaking, then, one might suggest that while it is far too optimistic to expect all individuals to attend and give to a church, a 10% tax on all those who do not might nevertheless fulfill the requirement of a wholesale 10% contribution to the needs of the poor. In order, of course, to ensure that the church-going folk are not double-taxed, their 10% tithes would be fully tax-deductible.
One might suppose then that an effective solution has been reached on how to sufficiently raise all those in the U.S. (this is an average for any given time) below the poverty line to above the poverty line.
It is entirely likely that many or most individuals living below the poverty line are in need of nothing near a full average income to reach the target of "above poverty line" and therefore a dedicated contribution of 10% across the U.S. would lead to excess money in the coffers of the government. This could certainly be used in other endeavors.

The basic point here is, a properly run tax system which requires a minimum 10% contribution of income from all individuals throughout the United States would produce sufficient income to more than provide for the poor in the country. Arguably this would get rid of the need for such complicated messes as welfare, unemployment insurance, and the like. The government would then need only to provide a number of things- a military, political offices (maybe less than we have now), a reasonable amount of public works such as libraries, prisons, mental institutions, postal service, and the like- in other words, that which fulfills government's basic Lockean role as protector of life, liberty, and the pursuit of happiness. I dare say that a populace given a relatively featherweight tax of 10% would be able to dig, say, another 5% out for such things (an estimated tax income of somewhere between 600 and 700 billion dollars. Or, lets be generous, a total of 20%. That gives the government, after dealing with the poverty line directly, a line of 1.2-1.4 trillion dollars with which to tackle other issues.
But I've almost forgotten- 10% of what the government gives back to the poverty line will come back to the government, so that's, for the sake of argument, say 120 billion more for the government to spend.
At 20% total out of your income each year, do you think MAYBE we'd be able to afford things like our own education no thanks to the public mess? And healthcare, for that matter? Personal management of income and funds is dependent on the work ethic of individuals, of course, but I think it's safe to assume that a dedicated population would have no trouble providing sufficiently for their children's education, health, and upbringing- especially if the government wasn't blowing so much money into the public education system that the price of education artificially inflates (cost of textbooks, for instance).
And, most importantly, such a 20% tax would not involve double-taxing churchgoing people who are already giving 10%- we would only be required to pay a 10% income tax on top of the 10% already given to the church.

I know, I'm asking for a lot of responsibility- but remember, where personal responsibility fails, regulation begins.