Everybody does live near a highschool, but that way you end with bad and good schools because of economic indifferences.

They are doing this (rather than just basing it on location alone) to spread the pain and more importantly give children born into this world the same chances irregardless of the social economic situation of their parents.

Locality still plays an important role, but we are talking high population density neighbourhood. Most will live near at least three schools in an radius of 30m walk (10min bike ride)