In my area, rents have gone up concurrent with house prices - but aren't falling now that sales inventory is falling, because those owners still want to cover the mortgage.
> property taxes should not be based on the "full cash value" of a property
That's not quite how property taxes are calculated, at least not in the two states where I sell real estate. In fact, even after a house has recently sold and there is a new market value established, the property tax basis doesn't increase up to that new market price. I just went through this with an out-of-area buyer, where I took the houses I sold last year that were comps to the one they wanted to buy and showed them the new tax assessment for this year. Yes each had increased, but nowhere near the market value (in fact, the tax assessed value was between 50-60% of the market prices).