But minor dependent children are assumed to not be providing for themselves, but rather to be the responsibility of one or more parents and/or legal gaurdians. This explains why the child's benefit is paid to the head of the household (and not the child), even though it is the child's benefit. Children's benefits are smaller than adult's because their necessary expenditure is lower.
Who gets to determine what is a "basic necessity" of life? Who gets to determine what cost level of these "basic necessities" is fair?
By accepting that we "have a right to have the basics of life untaxed by the government -- that's every man, woman, and child" then we accept that the government has the right to tax us on everything else. By accepting your reasoning, then we accept that the government owns all money and only allows us to keep what we want (or gives it back) based on what the government decides is "basic necessity" and what is an appropriate amount.
Show me where the right you describe has been defined?