1. A healthy nonzero vacancy rate of 5-10% reduces landlord pricing power. Unnaturally low vacancy rates work against tenants, not for them.
2. Did you know that rental properties which have been re-leased, but for which the tenant has taken occupancy within the last 15 days, are considered “vacant?” There are many other data problems like this — renovations, family homes, etc. Vacancy rates under 5% indicate essentially no available housing.
The solution has been obvious since the 1970s. It’s time to stop futzing around and build housing at the rate of population growth.