Are you aware that taxes on assets already exist?

https://www.irs.gov/businesses/small-businesses-self-employe...

The Estate Tax is a tax on your right to transfer property at your death. It consists of an accounting of everything you own or have certain interests in at the date of death (Refer to Form 706 (PDF)). The fair market value of these items is used, not necessarily what you paid for them or what their values were when you acquired them. The total of all of these items is your "Gross Estate." The includible property may consist of cash and securities, real estate, insurance, trusts, annuities, business interests and other assets.

How do they calculate the fair market value of closely held private businesses?

I wonder how countries like Norway and Switzerland implement their wealth taxes if this is absolutely impossible. It's true that more countries use an inheritance tax which has a similar effect to a wealth tax.