Earlier quoted context omitted.
You're right. I confused it with something else.
No problem. To an outsider like me, this seems like one of the worst features of Prop 13. Over time it separates people into two classes: those whose family has owned property for a long time, and everyone else who can't afford to buy a house because the taxes are prohibitive. (Even if you're very rich, it will make more sense to rent than to trigger tax reevaluation.) Call it neo-feudalism.
But that's also largely a factor of mostly high-income people moving in, while mostly lower-income people are moving out. Keep up the business climate that fuels the inward funnel of money, and you'll keep prices high. Even if you reduce restrictions to building supply, you'll have a game theory bit of not lowering prices in any hurry since people can so clearly afford them and are so clearly willing to pay them.