That's different. I'm saying once an individual has generated income and paid taxes on it they shouldn't have to pay taxes on it again. They should be free to do with that money what they please.
Just tax them appropriately the first time and then let the money be theirs to do with what they please.
I don't disagree with the bolded. However the gift and inheritance taxes are not on the person who earn it (and who paid income taxes), but on the person receiving, who is receiving it as income to them. That transfer is taxed. It's no different from a corporation earning profits, being taxed, then the employees are taxed when they receive a portion of the profit as income. New person/entity receiving it, new tax.
There is a federal estate tax, which is actually assessed when you die and your worth is transferred to your estate. This is paid by the estate, again, not by the original individual. The inheritance tax (in a handful of states) is then assessed on the income to the heirs when the estate gives money to the heirs.
It's one of the reasons people donate/establish non-profits to manage their wealth after they pass, so they can put it to a use they can somewhat direct ahead of their death (scholarships for vets, cancer research, zoos, whatever).
Example: you have earned 1 million and you die. Money gets transferred to your estate, federal estate tax on that transfer, payable by estate as it received income. Estate then gives to heirs, inheritance tax on that income, payable by heirs, as they received income. No taxes are assessed on the dead individual.
And all of this is to stimulate spending and circulation of money in the economy. If you spend your million before you die you create demand for products and services, and you increase the economy and jobs, and you pay sales taxes and such as the money moves around. Benefit to the economy is created, tax income for government is created. If you hoard it, great for you, but your kids then have to pay tax on that income, as they did not earn it and pay income/payroll taxes as they would have if they worked for it. No benefit to economy in this situation (due to hoarding) but tax income to government is still created, just after your death and in a lump sum as opposed to piecemeal in sales and whatnot throughout your life.