I asked the question on Twitter, but I don't know if I'm going to get any real answers or any answers at all over there. Here it is:
What's the appeal to taxing inheritance differently than other types of income? Aren't flat taxes bad and regressive?
I've occasionally encountered emphatic support for a 100% inheritance tax, but I'm never sure if that's not really a joke coming out of people's frustrations with nepotism and generational wealth accumulation. It seems like there are better ways to address those things than making exceptions to the progressive income tax.
Adding a 100% bracket just seems like a more coherent and consistent approach than trying to parse different types of income. In a similar sense, I don't think capital gains should be taxed at a different rate than other income either.