No, the law states that income from payment for labor is an ITEM of GROSS INCOME. Gross income != Taxable income.
Taxable income is stated to be GROSS INCOME less allowed exemptions and deductions.
You are merely begging the issue, and have no basis to stand on. Compensation for labor or services in the United States earned by United States citizens is not excepted from the inclusion in Gross income or calculation of "Taxable income". In fact it is expressly stated to be included into those calculations.
Your items/sources argument is a totally dead issue, as all income has sources and all sources unless expressly excluded by statute are subject to the income tax law.
See post 93 on the subject of "expressio unius est exclusio alterius," and the example of 26 USC §5841. It does not mean "all firearms unless expressly excluded by statute."
Taxable income is stated to be GROSS INCOME less allowed exemptions and deductions.
According to the regulations, you must first determine the source of the gross income, divide it into statutory groupings, and then use the operative sections which require determination of taxable income listed in 26 CFR § 1.861-8(f)(1) in determining taxable income.
Where is the operative section that requires determination of taxable income that applies to most US citizens?