"They are NOT married to one another. You try to illustrate as if the workings of zones / ports are intimate / intricate relationship written on stone.
.
It's just a job. New zones / divisions will take time, but it will work out eventually. They have to."
The relationships are quite intricate. These operations require considerable man power, work hours and infrastructure. Nobody...
more... would want to change them unless there is a benefit. And even in the cases where there are potential benefits from a changeover, they will not do it until all the easier options are exhausted.