I think what the author is pointing out is that the cost of tax is detached from the price of rent in similar houses in similar locations. That is, he is point

I think what the author is pointing out is that the cost of tax is detached from the price of rent in similar houses in similar locations. That is, he is pointing out that in the highly regulated market of housing (not even close to a free market) that Prop 13 does not help renters and instead favors long-standing owners mightily.