Ricardos law of rent working.

Ricardian rent or the Law of rent

The Law of Rent states that the rent of a land site is equal to the economic advantage obtained by using the site in its most productive use, relative to the advantage obtained by using marginal (i.e., the best rent-free) land for the same purpose, given the same inputs of labor and capital[

Essentially this means that the bargaining power of the renter can never dip below the produce obtainable on the best available rent-free land, because whenever rent leaves them with less than they could get on that free land, they can simply move to the new location.
So in essence if the rent is too low it will be bid up by those who can make better use of the land, whilst those areas where the rent is to expensive will become vacant.
 Land and properties that are vacant for a long time are simply priced above what the local market can stand.

Simples.