Comment by andrewla

No, my point is that two things both calling themselves a "land value tax" based on a putative "unimproved land value" can be wildly different in terms of incentives and results based on the specific mechanism used for computing that value, because there is a lack of any sort of objective reality underlying the assumptions that go in to computing that number.

At least for an entire value tax, we have the benchmark of "when a house is sold, how closely does the price hew to the imputed value for tax purposes" to determine if the tax is, in some sense, fair. Some municipalities do better than others by this benchmark, but many of them continue their totally broken methodologies (by the standard of predicting sale prices) for a variety of political and bureaucratic reasons.

For a specific attempted implementation of a land value tax, how do you go about measuring whether you are doing it well? You can sometimes get sparse data points when vacant lots go up for sale, but otherwise you're just benchmarking against other models.