A critique of property tax structures as they exist is not an argument for considering unrealized gains as income. One does not logically follow from the other.

A critique of property tax structures as they exist is not an argument for considering unrealized gains as income. One does not logically follow from the other. To steel man property taxes, land is immobile and requires certain government services even when it is unused (perhaps even more-so). Taxing that property is a direct an efficient(from a taxation perspective) way to fund the government services associated with that property.