On the distinction between ground rent and the rental value of the land  
plus building (improvements), professional valuation officers and estate  
agents currently examine both the physical state of a property and its  
location, taking account of market prices for similar or comparable  
properties. Where a parcel of land is currently vacant they can likewise  
infer its market value, both from the prices of similarly located vacant  
sites and by comparing the whole value of similar houses in different  
locations.  
  
As they say in Spanish: "Quien puede mas puede menos": he who can do  
more can do less. A valuation officer can (and does) calculate the site  
value more easily than the value of the building. Adjacent buildings are  
often much more heterogeneous than the value of adjacent land. Hence  
cadastral (land) valuations could be done more frequently and less  
expensively if site values alone were required for purposes of  
revenue-raising -- and with far fewer disincentive effects than with  
taxes on improvements.  
  
And as Adam Smith (Bk.I, ch.VI) also wrote: "As soon as the land of any  
country has all become private property, the landlords, like all other  
men, love to reap where they never sowed."  
  
Roger Sandilands