It is easier to reform an existing entity than to replace it with something new. Second, as political organizations, school districts must maintain a connection to the community at large. This is important now, if schooling is to remain a public good worthy of taxpayer support, especially when the vast majority of adults don't have children in school. Third, districts can bring substantial resources to bear in schools. In many cases, they can raise and spend tax dollars, providing a steady stream of revenue.
School districts can also recruit, retrain and re-deploy teachers, principals and administrators.
Most important, school districts offer a natural venue to seek an effective solution to the problems of equity and urban schools. Too often, the schools that are allowed to fail serve minorities, the poor and recent immigrants. Districts are responsible for all schools. Without some such entity accountable for a city's entire student population, the gaps between the succeeding and failing schools will widen. The failures of many urban school systems have chipped away at their legitimacy.