The Tax Code has a libertarian basis for this injustice. It regards the people as individuals, each of whom needs to contribute to the national government. This is so much taken for granted by everyone that it is not even questioned. In fact, there are other ways to view the US.
The founding fathers are not the font of all wisdom, but in this case they have made a good point. The constitution begins with the words, "We the People". It does not say anything about individual rights. It describes collective rights and obligations. The version of the constitution placed online by Cornell University, not surprisingly, does not capitalize the word, "People", but the capital "P" is there in the original. The rest of the preamble continues with the collective viewpoint. The Constitution is formed
in order to form a more perfect union, establish justice, insure domestic tranquility, provide for the common defense, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity.
The framers of the constitution clearly intended the newly created government to serve the interests of all the people.
Some would argue that rich citizens should not pay more taxes than poor citizens because they don't use more government services. This was clearly not the intention of the framers. They showed not the least concern about fairness of revenues, only that citizens could not be taxed without representation -- as a group, not as individuals.
In fact, though, the rich do receive greater benefits from the government than the poor, because they have much more to lose. The laws protect their property from confiscation without due process, a protection also afforded the poor, although they have no use for such protection. The armed services protect the rich from foreign invasion to a far greater degree than the poor. The poor might lose their rights but the rich would lose all their possessions in addition to their rights if the country were invaded by a hostile power. But the primary purpose of the armed forces is to protect overseas rights of American businesses by keeping the sea lanes open and assuring that US trade and overseas possessions are protected. One goal of warfare since the end of the Vietnam War has been to assure the free flow of oil, a goal supported primarily by the owners of corporations that depend on oil. Such benefits are of little use to the poor, who would be better served by domestic sources of energy.
The Constitution itself recognized that the wealthy would receive more benefit from the government it created. While all the people were to be represented in congress, only the property owners could vote, hardly surprising since the framers were primarily wealthy property owners. Furthermore, the wealthy framers intended to benefit themselves above all.
In practice, while the wealthy give money to support the government, the poor give their children for military service. Those who claim that the wealthy don't get more benefits than the poor do not take into account soldiers who have risked death or died to preserve the rights of others to amass property. The wealthy of late have resented having to provide benefits to those who fought for them and their survivors. I suppose the rationale for this is that the poor must fend for themselves regardless of their service to the nation.
The government itself (EPA) calculates the value of a single human life at $6.8 million. Do the families of fallen servicement receive any similar compensation from their government? In many cases, what they get is a thankyou, a free funeral, and a flag. Where is the justice in that?