[kelnos]

Taxing at death would be double dipping.

Not really the point. In general, money is taxed when it changes hands. Payroll taxes, income taxes, sales taxes, etc. Taxing on death is just taxing money that is transferred from the decedent to their heirs. It's not a matter of how many times you "dip": the same money has likely been taxed quite a few times for different reasons before it ended up in that person's estate anyway.