Large districts may desire complicated, customizable systems to meet their unique needs. These "enterprise" software customers want to tailor systems to their specific requirements, and don't believe "off the shelf" software is adequate. They realize that these complex products don't run right out of the box. They understand that significant labor investment, in the form of up-front software development and long-term maintenance, is needed to deploy and manage enterprise systems.
Districts with large technology departments (typically over 50 employees) may have the capacity to successfully own and manage software. This means that they have skilled technology staff that can perform sophisticated customization and long-term maintenance on a system.
These measures are significantly costlier than the Cloud. Districts undertaking these tasks don't benefit from the economies of scale experienced by vendors servicing hundreds or thousands of customers. These "do it yourself" owners believe their unique needs justify the added effort and expense.
Customers who regularly build software and have developers on staff could conceivably benefit from traditional software. These districts probably also want the source code so their developers can modify it. They expect vendors to provide software development support.
Districts that already run highly available data centers could potentially deploy software applications with cloud-computing quality. If these customers understand how to implement redundancy and high availability like cloud vendors, they might deliver reliable applications with traditional software.