That "figure out the median property value" is the hard bit.

The value is determined in a voluntary exchange, such as a sale, and results of sales of similar property serve only as approximations.

Same problem is with the land value tax. It's like trying to buy / sell your property every time you do taxes.

There is a known mechanism to limit attempts do show an excessively low value. Back in the day, the British Empire's customs reserved the right to immediately buy the entire freight of a merchant ship for the value declared at customs. That could work with land and even realty, too, but would be much more disruptive.