Why does the income tax law omit liability of the average working American?
The income tax law omits liability because the Constitution does not permit the federal government to tax personal earnings. In other words, it would have if it could have, but it couldn't so it didn't. The Constitution prohibits the federal government from taxing property or person without apportionment among the States. By taxing 100% of personal earnings, the tax is being applied not only to the profit, if any, (income) derived from wages and salaries, but also taxing the human capital (your effort, knowledge, skill, energy and labor), which the Supreme Court says is your PROPERTY, that you invested in order to receive the wage or salary.
"Income" is not what "comes in", but only the profit, or gain. The IRS does not contend that any other gross receipts are income, only that portion of gross receipts that are above and beyond the investment required to receive them. For example, if one purchases property for $100 and sells it for $150, the IRS taxes only the profit. If it taxed more than the profit it would be taxing the $100 investment, called the "basis", for the property, and that would be an unconstitutional property tax.
As for your personal earnings, however, the IRS contends that your basis in those wages is "$0", making your personal earnings 100% profit or income. If you believe that you give and invest absolutely nothing to deserve your pay, then you would agree with the IRS. If, however, you believe that you have invested a part of your life span, a part of your limited work life span, your energy, your labor, skill and knowledge, all of which are your PROPERTY, then you can only conclude that the IRS is taxing your property, a tax prohibited by the Constitution.
In addition, the Supreme Court has repeatedly held that your right to earn a living for yourself and your family is a God-given fundamental right, just like your freedom of speech and your right to worship as you choose. The federal government cannot tax any fundamental right because if it could tax that right it can restrict and even destroy it. Personal earnings are, therefore, exempt from federal taxation.
If the income tax law identified those whose income can be taxed, it would have to reveal those whose "incomes" cannot be taxed. That is why the income tax law does not include the average working American as one who is liable for the tax. For the same reason the tax, limited to taxable income, and admitting that it taxes neither exempt income nor income that is not profit or gain, does not impose any tax on personal earnings.