Some of thee most amazing rightwing doublespeak ever created has to do with inheritance taxes. And that shouldn't come as a surprise- those affected by it have more than enough money to hire the best mouthpieces available.
The first thing we need to clear up is the notion that taxes have already been paid on inheritances by the grantor. That's not true. Stocks, bonds, art, antiques, and real estate purchased decades ago and never sold have appreciated tremendously, and no taxes have been paid on that appreciation, ever. If there were no inheritance tax, there would never be any tax on it...
As has been pointed out, estate taxes only affect .2% of all estates, and even that figure is deceptive. A $2M estate would pay nothing this year under current law, but a $2.1M estate would be "affected", with estate taxes having to be paid only on the amount over $2M... meaning that an even smaller % are "affected" in ways truly significant...
And I think it's important to realize that virtually all earned income is subject to income taxes. So if the grantor of the estate has employees, they pay taxes on their money... Which we don't see as "double taxation", at all... but when the grantor dies, the heirs are taxed on money they didn't even earn, which is somehow interpreted to be "double taxation".... which is malarkey...
One of the biggest problems with untaxed inter-generational accumulations of wealth is that it tends to concentrate wealth and power into the hands of a very, very few people, who have done nothing to earn it, at all, other than being members of the lucky sperm club... and many of the assertions and conceptualizations used to defend such are based on the infinite pie theory, which is an entirely false view of finite resources available to the human race.
Sam Walton, just for example, became exceedingly wealthy on the merits of his own endeavor, and I have no problem with that. His heirs are another story entirely, particularly those who will arrive several generations down the road. Which is not to say that they shouldn't be allowed to inherit, at all, to not be financially secure from cradle to grave, nor does current law demand that. But it's important to realize that huge accumulations of wealth are near static, actually contributing little to the economy thru turnover. And that's what's fundamentally wrong with many third world economies- all the wealth is held by a very, very few at the top, so much so that what we see as a middle class simply can't develop. Even as such economies can be said to "grow", the benefits of it go straight to the top, and stay there...
Many of America's wealthiest families are old money, and much of that money is held in Trusts, an artifact of the compromises of the New Deal. Their problem is that trusts can only benefit persons living at the time the trust was created, and they're running out of such heirs... That wealth has grown tax free for generations, but when the last of the eligible heirs pass on, that inheritance becomes taxable, something they're desperate to avoid... It's not like any of the affected heirs will be made destitute- they still stand to inherit vast sums...
But those at the top really hate paying any taxes, ever- to them, the govt is something they make money off of, not vice-versa, so they've engaged in a decades old campaign to sway public opinion and congress that almost worked- the recipients of their largesse were so desperate to get it through that they even tried to make it a condition of raising minimum wage. Pretty shameful, really, but not at all surprising...