Although many begin as conquests by gangs of armed men, jurisdictions are well founded when they are voluntary associations of people agreeing on a social contract, with consistent legislation evolving thereafter. The citizens of isolated towns may agree to start schools, with no obvious injustice committed; but as these towns grow, and their developed borders come in contact with each other, inequalities may become obvious, with the more developed towns having a natural instinct to preserve their advantages by excluding their neighbors. Similar tensions can arise around all kinds of borders, with poorer peoples being tempted to invade and seize what they don't have other access to, and richer peoples establishing armies and other enforcement officers to defend what they have; and poorer peoples may give up any attempted armed invasion in the face of superior force, and instead attempt isolated acts of covert economic immigration, and then try to change the laws and the culture of the countries in which they've newly arrived; and this may prove more effective than any armed attempt might have proved, especially insofar as they are arriving in jurisdictions with many liberal hearted, sympathetic citizens.
Insofar as established resources are the material manifestation of past labours, the possession of resources such as well endowed schools cannot be regarded as unjust; but insofar as they are the result of having fortuitously inhabited lands with superior natural resources, and especially when it is one's ancestors who have done so, and have forcibly dispossessed more primitive peoples who were there first, such superior inheritances are unjust. When some children inherit much more than others, with the well off ones having exerted no labour that might have earned such superior resources, injustice has definitely arrived, through the inheritance of unearned wealth. Thus humanity requires periodic redistributions of wealth, or social tensions can become unbearable.
Justice requires fighting the instinct to preserve unjust, unearned material advantages for one's children.
Local school districts are unjust because they depend upon enforced invisible walls that preserve unequal, advantageous resources for undeserving, fortunate local children and exclude those with a valid claim to an equal opportunity in life.