StorageObjectInUseProtection feature is enabled by default in K8s 1.10+. Assume K8s cluster is used with this feature enabled, i.e. finalizers are added to all PVs and PVCs. In case the K8s cluster admin disables the StorageObjectInUseProtection feature and a user deletes a PVC that is not in active use by a pod then the PVC is not removed from the system because of the finalizer. Therefore, the user will have to remove the finalizer manually in order to have the PVC removed from the system. Note: deleted PVs won't be removed from the system also because of finalizers.

That's why pvc-protection-controller is always started because the pvc-protection-controller removes finalizers from PVCs automatically when a PVC is not in active use by a pod. Also the pv-protection-controller is always started to remove finalizers from PVs automatically when a PV is not Bound to a PVC.

Related issue:
https://github.com/kubernetes/kubernetes/issues/60764

Related PRs:
https://github.com/kubernetes/kubernetes/pull/61370
https://github.com/kubernetes/kubernetes/pull/61324