The tax evasion argument doesn't seem to follow. It's not the scarcity that you want hard to measure it's the value. Scarcity in modern art is always assured

The tax evasion argument doesn't seem to follow. It's not the scarcity that you want hard to measure it's the value. Scarcity in modern art is always assured by one of a kind or limited runs. If it's photorealistic it's much easier to judge the value than an abstract composition. How much should a shark in formaldehyde be worth? If it's in a natural history museum, then the price of the shark, the tank and the formaldehyde and any labor to prepare it. If it's in an art museum, who knows? Whatever someone paid for it.