Comment by aspenmayer

No man is an island, unless you're Robinson Crusoe, who was a character in a story.

No parcel of land is an island in this sense, not even an island, because what makes an island is its being independent of a landmass or continental shelf. But in the sense of being moored, all land values are grounded in discrete monetary terms. Even if they are subjectively determined, the land value is an idea space that has limits on what concerns are common, and thus are typically already priced in, and concerns that are less common, and may have already been sold, such as mineral rights.

Unimproved land value is value relative to comparable[0] plots in that same market if possible, because it's meant to be as close to apples-to-apples, all-else-being-equal as it can be. The basis for comparison is whether it's improved or not, as you seem to be specifying, so the relation of land value to improvements seems to be the only independent variable that a potential or actual landowner or anyone else could even manipulate, even in a hypothetical where we aren't bound by real-world factors or limits.

[0] https://en.wikipedia.org/wiki/Comparables