Inheritance is not about the children.
You ask whose labour is seized by a 100% death tax? The parents’ labour. That’s obvious enough that I feel I must be missing something. What was your (presumably?) rhetorical question supposed to make me consider?
Inheritance is a way to get people to contribute towards prosperity for the future of the human race...by convincing them to contribute towards the prosperity of Bob, their beloved son. Maybe you don’t need a personal connection to take selfless actions, but that’s not universal: I bet that a 100% death tax world would have a lot more golf courses and cruise ships funded by reverse mortgages and premature sales of family businesses.
A low inheritance tax tells people that they can have a direct impact on a cause they care about (usually their children) after their death. A 100% death tax tells people that they can have as much of an impact as typical government funding on the causes the government spends money on.
I know which one would motivate me to be a better steward of my wealth.
Yes, I make that assumption. I believe I’m in very good company there, with both the general public and (many, but not all) decision theories/moral systems recognizing agreements that carry on past death. Why would you think otherwise?
I’m not quite sure what this post’s hypothetical is supposed to be, but sure. Let’s say that charitable donations are fully exempt from the tax.
People don’t care about charity to any substantial extent. Donation rates are around 4%, whereas raising a child averages 15%ish per child for nearly half of a parent’s career, never mind the non-financial investments in their wellbeing. It’s not a complete restriction on giving, but it cuts out the most important one in many peoples’ lives.
Allowing for charitable donations as an alternative to simple taxation does shift the needle a bit but not enough to substantially alter the argument IMO.
No, they absolutely are not. Spending your money before your death is heavily constrained by uncertainty. The chance of sudden unexpected death between 20-64 totals about 1.5% (calculated from here), and the anti-loophole protections would catch more. Even outside of the worst-case scenarios, you will always die before a sufficiently-optimistic estimate (and if you aren’t optimistic enough? Have fun living out your last days while completely broke, I guess.)
To be clear, I was talking about the parents being good stewards by managing the wealth for the benefit of future generations (i.e. Bob, and perhaps his kids). I have opinions about how effective the government would be compared to the children, but those differences pale in comparison to tearing everything down to get the last drop of value out before you die and lose it all.