Because enterprise systems were typically written by people who no longer work for the enterprise (and may no longer be in this plane of existence), because the

Because enterprise systems were typically written by people who no longer work for the enterprise (and may no longer be in this plane of existence), because these systems have been adapted over long periods of time to applications and platforms that were never anticipated during the original design, and because writing, testing, and deploying large-scale systems is still not well-understood. Predictive optimization may have something to do with it, in the same way that maybe RMS Titanic might not have hit the iceberg if they'd been able to make the gin-and-tonics consumed by first-class passengers colder.