I'm not following your last statement. Land is already taxed on its assessed value, which changes regularly, and things like cars have easy to find residual va

I'm not following your last statement. Land is already taxed on its assessed value, which changes regularly, and things like cars have easy to find residual value estimates from third parties. You wouldn't necessarily get the true market value to tax, but getting some baseline value wouldn't be particularly difficult. The only exceptions I can think of are really intangible value stores like artwork.