You don't read Jesus much do you ? The Widow was poor and Jesus praised her for giving in greater purportion than the wealthy gave. The poor in the USA , if they work, might give more in purportion than some very wealthy provided you count the sales taxes that are more avoidable for the wealthy and FICA which is entirely avoidable for the very wealthy. It gets even worse if the Poor guy is a home or farm owner because when he sells his property (or dies)he is subject to the laws for taxing the rich temporarily.But without the rich guys ability to use accountants and specialised Lawyers.
======================================================================
You still don't get it. The widow gave a paltry sum. It was insignificant when compared with the donations of the rich. It was ONLY when taken as a percentage of her net worth that it became meritorious in comparison with the percentage of net worth donated by the rich.
Why was it meritorious? Obviously because it represented the greater sacrifice.
Was it FAIR? Jesus didn't say that the widow's mite was fair to the widow. That would be absurd. The widow shouldn't have to sacrifice MORE than the rich.
The widow's mite parable provides a way to measure love, not fairness. But in making his point, Jesus implicitly assumes what we all know, that the measure of sacrifice (not of love or of fairness) is the cost to the donor. The effect that the sacrifice has on the donor.
The measure of the tax sacrifice, therefore, in terms of FAIRNESS, should be not the net sum of the donation, but the COST to the donor of making it. Fairness demands that all sacrifice equally. If the tax rate were set at 50% for example, many paying the tax would not be able to live, while the rich could continue on as before.
Therefore, in principle, a flat tax is unfair, unless it is set so low that nobody, not even the poorest, is unable to meet basic standards of living after paying it. This is patently absurd. The only fair way to raise the taxes needed is to graduate the rates and make the rich pay more.