Actually, the restricted record wasn't out of wedlock. Many city clerks won't hand out birth records for people who are potentially still living. They'll only give it to someone named on the record, unless you can provide a death record. This particular person was still living, & had to get the record themself by providing a copy of their photo id. I know I've had to do the same to get a copy of my own birth record.
Also, if someone was adopted, it is difficult to get the original birth record with actual birth parents. I know some people who were adopted & had trouble acquiring their own original birth records.