The idea is that you are taxed based on your own estimate of the value of a thing, with the estimate being public and binding as a sale price.
This sounds incredibly simple, with a natural mechanism of enforcement; if you undervalue a thing to pay lower taxes then you risk losing it at that price.
But I don't think this would work in reality. Pricing things is super hard. In a very liquid market it is difficult but doable, in an illiquid market (of one non-fungible asset) it is practically impossible. At what cadence do you update the estimate? How long is it binding for? If the value suddenly changes, how long a grace period do you have before you have to update the price?
You can try to patch this by saying that you have a right of first refusal -- that if someone offers to buy the asset at the price then you can accept their valuation as the new estimate of the price, and pay taxes going forward on the new value.
But then this defeats the point of the process because effectively the valuation is non-binding. So you have to put in all sorts of structures to prevent abuse -- maybe levy fines for past underpayment when the pricing is adjusted, or limit the number of re-pricings per time period.
And it incentivizes nuisance bidders, because owners will defend their property. So you have to put in restrictions like forcing escrow before the sale, or limiting bidding by a single entity.
Not to mention the difficulty in maintaining this registry of ownership of these assets, along with how to deal with more complicated deals about the rights involved -- film rights vs. tv rights vs. print rights, rights to individual characters, temporary licenses, etc., and all of that needs to be mechanized to allow a certain fixed list of the types of rights that can be granted, which right now is as extensive as a contract can contain -- if Sherlock Holmes were still in copyright, what if I just wanted to license Watson or make a film about Moriarty?
This is all just hopeless technocratic pie-in-the-sky dreaming.