I read the Opening Post as though Andcarred is referring to New South Wales BDM restrictions for accessing their marriage registrations. I doubt there's many ways to determine my maiden name without accessing NSW BDM records.
JM
You must have a limited internet presence. My mother's maiden name and my maiden name are online with the SMH notice of my birth. Very easy to find. My marriage notice can also be found in the NSWSL and the NLA SMH images. My mothers maiden and married name is on her memorial inscription and on the funeral notice which can be found in local newspapers (index on the Ryerson Index). My married name is on that funeral notice, so not difficult to determine my maiden name from said notice. Her maiden name is also in archive records related to her profession before marriage. My husband and his siblings can be found in the Qld archives school records.
I didn't know it was compulsory on this website to discuss only the exact item as mentioned by the OP. As I demonstrate above, there are many ways to find out a person's maiden name without reference to the NSW BDM records. Consequently I don't have a problem with finding my marriage in the NSW indexes.
I understand that others may not agree with me, but I disagree that the information for many people cannot be found elsewhere, I have found it for many of the people I have researched without access to their marriage certificate.