Neil,
Some of the various clergy in the various denominations had a great deal of difficulty coming to terms with the civil rules which oft clashed with their own church practices... particularly when it came to informing the civil authorities about members of their local parish. NSW parliamentary debates went on for DECADES and decades ... There was a great deal of mis-trust betwixt the civil and the ecclesiastical institutions... and they all had funding issues ....
What you are finding, doesn't appear to be any more odd than what I have found when tracing my tree back. I have the benefit of a wonderful set of family papers with various detailed records passed down to me going back on one NSW line to 1817, and it took me several decades to work through confirming/rejecting those details, getting certs, saving up for more certs etc. I have also re-validated the info since the internet came along, and more especially since that wonderful digitised newspaper site, TROVE ... came to my puter.
As I see it, you are only noticing the apparent long list of NO CERTS because we have been able to 'concertina' your searchings into such a short time span ... the tyranny of time being almost overcome by the internet and the current popularity of family history leading to so many resources being uploaded.
I remember my late gran who explained to me that although she was orphaned before QV had made Australia a Federation, some of my Gran's family had arrived in NSW before QV was ever even a twinkle in her Dad's eye. I inherited my Gran's "genealogy" notes books back when children were not permitted to even ask for access to the Reference books in the main (Adult) library. But our local librarian understood my desire to learn, so she turned a 'blind eye' as I devoured anything to do with NSW ... What a change in emphasis I have noticed in the way history is researched, themed, delivered and devoured over the past six decades or so...
Cheers, JM