Earlier quoted context omitted.
1) For assets hard to value, the owner would have to declare the value of the painting. They would pay taxes on that declared value. To prevent the value from being too low, anyone would also have the ability to purchase that asset at the declared value.
You clearly haven’t thought through the implications of that policy. It is literally forcing the owner to write a call option against their asset that anyone can exercise and without the owner receiving a risk premium. Speculators and arbitrageurs would make a fortune acquiring these assets if the call option was written at fair market value. It would be like r/wallstreetbets but with everyone’s private property. Tha…
There are several solutions to this hypothetical problem.
The parent said the owner decides the value of their premium item. The owner is claiming indifference as to whether it is sold at their chosen value or not.
If that's only fair market value (in the rest of the market), the owner is indifferent to owning the asset at all and is just inadvertently hoarding it. The economy works better for everyone if the owner is encouraged to sell to whoever values it most highly.
If the call option is called in (above the owner's valuation plus costs), an auction could be triggered, avoiding the arbitrage of first dibs.
Overall, this is a hair on the back of a nit. The law should be that you pay tax on your global wealth - avoiding and evading tax is already a choice that people make. It's nothing new.