In the US:

>As of 2021, only estates valued at $11.70 million or more are subject to federal estate tax.

No sympathy for people who think that sort of windfall from their parents should somehow be untouchable.

Yes, I think you may have misunderstood what I said. There are people worried about the threshold lowering, e.g., taxing estates of only a few hundred thousand, or perhaps anything (I'm not saying a lowering to this degree is remotely likely.) So they complain about the estate tax at its current levels. It's an example of the tug-of-war mentality that appears in much of American politics.

If it did get lowered to affect normal people it'd only be from the efforts of rich people to poison the well against the taxes.

Interesting theory. I haven't read of any lobbying to that end (most seems to go into favorable windows and other means of exemption) but it would certainly create a larger block of opposition.