No matter what sort of static validation they attempt, they're still risking other unanticipated effects. They could stumble upon a bug in the OS or some driver

No matter what sort of static validation they attempt, they're still risking other unanticipated effects. They could stumble upon a bug in the OS or some driver, they could cause false positives, they could trigger logspew or other excessive resource usage. Failure can happen in strange ways. When in a position as sensitive as deploying software to far-flung machines in arbitrary environments, they need to be paranoid about those failure modes. Excuses aren't enough.