You handle that the same way income taxes do: the first X amount is exempt, like a standard deduction, applied to the land under someone's primary residence. Pair it with a rolling multi-year average for assessment so value spikes phase in gradually instead of hitting all at once. Keeps the incentive against passive land-holding everywhere else intact, without the blanket caps that also protect speculators. Instead of using one tool to fix it all, you use multiple tools that work together to make efficient systems