I fail to draw the same comparison, but that's not unique my friend. :)
On the road, "frontier" "unused" "common-good" land delivers benefit to the general public by way of open spaces, natural resources, scenery, production of oxygen. On the internet, unused domain name provides very little in terms of benefit and/or detriment to the general public. To the professional domainer, an unused domain represents a potential market derived from a commodity who is waiting for the cost of production to be less than the inherent market value.
As domainers branch out from type-in-traffic, product category, lead gen asset purchases into generic/future brands, new TLDs, etc less and less of the commodity will be available for the general public.