You are not paying taxes on the unrealized capital gains made from buying your car. Can you imagine if your Tesla was deemed to have a market value of 2x what

You are not paying taxes on the unrealized capital gains made from buying your car. Can you imagine if your Tesla was deemed to have a market value of 2x what you bought it for, because a few random idiots were trying to buy it up? And you had a gigantic tax bill on that? Unrealized gains are not gains. What 'someone else' is willing to pay for your property isn't necessarily very well related to how you value it. It might possibly work for real estate in controlled conditions but even then it's risky. For equities, it's really hard to have an asset tax.