As I understand it, what prompted Prop 13, aside from the desire to serve the owners of the best land, was that while land values were rising astronomically, municipalities and elected representatives were eager to serve their constituents, who naturally wanted all the amenities that their governments cared to offer.

And the municipalities -- their local elected representatives -- complied. They didn't reduce the millage rate each year to stay revenue neutral. No, they used those funds to supply those desired public goods.

And as land values rose, taxes rose. And eventually, people whose homes were appreciating by half (or 100% or more) of their annual incomes, increasing their home equity at an awesome rate, started objecting to the taxes that were paying for all those public goods.

Remember that in those days, California's colleges and universities were regarded as among the very best. And they changed a lot of lives, particularly of those in the school districts so well funded by those taxes that were ever-rising because the local officials didn't lower the tax rate to remain revenue neutral.

I don't see any sign that California, under Prop 13, has any resemblance to Georgism.

Take a look at a listing at realtor.com for a home in any California city or suburb, and focus on the "Property History" section, on (1) asking and selling prices; and, under that (2) assessment and tax history. (Choose the "see more" option in each section.) Then look at the assessments vs the current asking price. The land and "additions" figures rise by no more than 2% per year, while the asking and selling prices are far above the assessment on which taxes are based.

"The land value component is re-accessed frequently and changes based on comparables (presumably but its mostly black box)." No, they rise by 2% per year, until a sale takes place, at which point their sum is adjusted to the selling price.

But the house next door, of similar age and condition, but not sold in 20 or 40 years, is receiving a huge subsidy, paying a tiny fraction of what the newly sold neighboring buyers are paying.

Where is the equity in that?

The answer, for other states, is not assessment caps or capping taxes at a certain percentage of assessed value, but reducing the millage rate to remain revenue neutral, unless the local property owners approve a millage rate that is higher than revenue neutral because they actively desire more services, better schools, etc.