>it is the interest rate - because the price of property is related to the cost of money (aka, interest rate).

You can manufacture more cars and houses as you get more money. It clearly is related to the fact that land yields a risk free return regardless of what you use to price it.

In that sense money and land is an NRA. A non reproducible asset. Low interest rates break the NRA property of money which is perfectly ok if inflation is also low. Rather than holding onto money unproductively they simply switch to holding land unproductively. The solution is to introduce a holding fee onto land.