One of the reasons that NYS has restrictions on birth certificates is because
of adoption advocates who, at the turn of the century, felt that it was in the
best interest of the child, birth mother, and adoptive parents to keep each
party's identity a secret.
There are other reasons to keep a birth certificate private. For instance, it
prevents people from assuming a false identity.
I'm not sure why death and marriage certificates are private. Perhaps Ruth
Ann some insight into that. It does seem kind of silly to keep them
confidential when every direct marketer in the nations seems to know our
private business anyway.