In Payment approval creator is not able to approve the created batch. How is this enforced.

We have received questions from the external auditor on the payment approval process. In BPM Task Configuration the option 'Prohibit user self approval' is not setup. Still if a user creates a payment batch the user is not able to approve his or her own payment batch.
Auditor has asked for documentation or explenation on how this is enforced even though the option in the Acccess Tab on the Configuration Task is not enabled. I will upload screenshot of the Task Configuration setup.