There are grades of land. Land in the city is more scarce and more valuable. Rural land is less scarce and less valuble. Land on Mars is even less scarce and less accessible and less valuablee.

Same with domain names. People are interested in using shorter domains like abc.com, not long ones such as xyajfbeusnfdbdjak.craptld

The scarcity applies to a grade of land or string, not to all land in the Universe or string space in total.

It is difficult to compare the 'grades' of land, because the grading is not discrete but somewhat continuous.