Not easily convertible to cash.
Doesn't fix the government's spending pattern or plug its budget hole unless it resorts to full on expropriation.
Not competitive.
So if you try to game the system by not claiming a vacation home, it just becomes public property.
Thoughts?
The LLC with the innocuous name of 123 Main St LLC which is the owner of the property at 123 Main St definitely has an owner, and it might not be a tax resident because the LLC is owned by 123 Main St Limited in the Cayman Islands and the ultimate beneficial owner, who is still unknown at this point, may not be an American to begin with.
So just applying heuristics to "hey that house doesn't appear in our tax records get it boys" would create more problems than you think.
And this also circles back to "not competitive". If your country has problems with expropriation people will stop coming there, and others will leave.
But also note, the US constitution does protect against expropriation in the 5th amendment. When rich people start being the subject of civil asset forfeiture the 5th amendment will suddenly start applying again.
3 and 4 are the real problems with a wealth tax.
The fundamental issue is that the government spends too much money. The politicians and the voters who support them refuse to support cuts in the magnitudes necessary to bring that situation back in hand. Many don't even believe it is a problem. On top of all that, the programs they refuse to cut, at every governmental level, are exactly the programs that suck up the most money. Medicare, Military, Police and Fire, on and on.
99.999% of all voters are like the family in the financial advisor's office who are willing to cut the trips to Starbuck's or go to a cheaper gym. So they feel they are being responsible. But they tell the financial advisor that the kids' private school tuition and the $50,000 cars they drive are not up for discussion. (Lord help you if you have the temerity to bring up the biggest issue of all, the $500,000 house they live in. You better have you kevlar on for that discussion.)
What can you do with people like that?