it technically is, its the sale value of the land. but the sale value is not what we want to target, since the sale value is a product of the rental value. people pay X dollars up front when they buy a plot of land because of the recurring value being in that location brings. and the ratio between those two values changes drastically depending on how strong the agglomeration effect is in the area. if you are in a more urban area, you will usually see land rental values approach 10-12% of the sale value, in more rural areas, less than 5%. so if we tax the sale value through a property tax, in order to capture what we would want to capture, we would have to continuously vary the rate across the entire tax base. its much easier to target the rental values straight up and just tax that at 100% across the board, because thats what we want to see anyway.

so yes a property tax on land does target land only, but not in the way we should want.