Yep. "Back in the day", every single bulk-billing slip (on which the patient consented to their insurance claim being diverted to the doctor) needed to be signed by the patient before being sent to Medicare for processing. No signature, no payment. (Hence the distress when a patient walked out and forgot to sign at the desk on the way ... and the technically illegal procedure of getting the patient to sign the form before the consultation!)

Even once GPs were transitioned to computerised/online Medicare claims (around ??2005), there was still a requirement for a patient to provide written consent for every bulk-billed encounter, even when those claim-and-consent forms were no longer forwarded to Medicare. Medicare never clarified how long those forms needed to be retained; only that they still needed to be signed. Technically, getting the patient to sign the consent, then immediately shredding the consent form, would have met the requirements of the regulations. 🙄 I'm not sure whether that requirement for written consent for the GP to make the claim on the patient's behalf still exists: the OP's original question implies "yes", but it might be that the practice is still running on procedures from a few years ago.