> ... These assessments would require intricate and subjective valuations that are very difficult to quantify accurately.

I continue to believe that "full cash value" assessments which try to ascertain the market purchase price of real estate are very foolish. And there are so many inputs and methods of formulating an assessment. What all of them have in common though, is that they consider the rental value of the property. It would be so much simpler if the tax was only assessed on the rental value. It eliminates things that effect the sale price estimates like interest rates, subjective risk tolerances, speculative premiums, and even the tax itself. The tax rate on the rental value would of course be much higher than the tax rate on the purchase price (25% compared to 1% for example) but it's a much more stable assessment with a lot more reliable data backing it up.

disclosure: I am a Georgist and former president of Common Ground California.