Why not handle changes in land value the same way we handle changes in value of personal property?
Suppose I hire a young, unknown artist to paint a portrait for me, for $100. Thirty years later, the artist is very famous and recognized as one of the most talented and important artists of his generation, and his early works (such as my portrait) sell for tens of millions of dollars.
The way we handle taxing that tens of millions of value that my painting gained is that when I sell it, the difference between the sales price and what I paid counts as income (probably long term capital gains income in this case), and I pay tax on it.
Property taxes are usually used to fund local government and the services it provides. Those don't really correlate well with the value of property. My house and land are assessed about twice as much as that of my neighbor two houses away for instance, and about half of my neighbor across the street, but we are all provide about the same burden on the city for services and all reap about the same benefits.
Thus, I wonder if the way we should do this is that property taxes to fund local government should simply be per lot (or maybe per family, or something like that), and not be tied to the market value of the property. The value of the property would figure into income taxes, when those changes are realized during a sale of the property, using the same rules that we now use for personal property.