Existing tax policies focus on the current market value of the land. Compared to a land value tax, existing tax policies assess poorly used land or vacant land pays much less in taxes. It encourages speculation and discourages productive use.

The assessor can't the share of land vs structure unfairly any more than they can increase the assessed value. A homeowner can protest the assessment and provide comparable sales and other estimates that show a more objective split of value.

Michigan property taxes are interesting in another way, they have had issues with "dark store" restrictive covenants for commercial and industrial real estate. Basically the owner of a large commercial building argues the land/building has very little value on the open market, it is a single use building with restrictive covenants that prevent an alternative use. These restrictive covenants prevent the land from being sold to their main competitors, and these restrictive covenants are self imposed.