I wonder if some sort of "non-person wealth tax" is mechanically feasible.
The goal is "big piles of money eventually go away"; estate/inheritance taxes stand at the boundary of individual ownership to try to chip away at the big piles of money when it is passed from one generation to the next.
The "loophole" is that non-person entities, in the form of corporations or trusts, do not die. Your family establishes a trust, dumps money into it, and within that trust it can be invested and grow indefinitely, even if money is taxed as it is taken out.
Assuming we don't want to just make non-corporate entities mortal -- require them to "die" and be replaced by a successor organization every 60 or 80 or 100 years -- the problem becomes "how do we keep an immortal entity from just sitting on an ever-growing pile of money, indefinitely".
So what if we just created a wealth tax and applied it to these immortal entities, of, say, 3% per year?
Could you apply it to all non-person entities, family trusts, for-profit corporations, non-profits, universities, etc? (If there is an exempt category, you're obviously going to suddenly have a lot of family chapels with billion dollar endowments.)
What would be the side effects, and which would be positive and which would be negative?
Assuming you taxed for-profit corporations on their wealth, and adjusted corporate income taxes appropriately, which sectors would benefit and which would go away? Would it be a good or bad thing for those sectors to become non-viable?
How hard would it be to reconcile internationally, could you tax entities sanely for the portion of their wealth resident in a jurisdiction, or would it be impossible to do fairly without leaving big tax havens?