As brief as I can this is what happened.
Regular weekly silver QFF flyer for work - charter flights. Arrive at airport 45mins before departure (as per recommendation) same as always - done this many, many times. Step up to the bag drop (QFF bag tags) to check single bag and machine can't read the tag. Readjust the tag orientation. Still can't read. All other bag drops occupied with queues. Readjust tag to point bar code at camera, still won't read. This goes on and on. Same tag as always used and used subsequently with no problem. Manage to attract attention of disinterested ground staff, who proceed to try exactly the same things. Eventually after many attempts, the bag drop machine decides to start working again and the bag is accepted. It starts being carried away on the conveyor, then stops, reverses and a message comes up on screen saying "Bag cannot be accepted at this time - see ground staff". It is now a few seconds less than 30mins before the schedule flight departure time.
I proceed to the ground staff and ask them to manually check the bag as the bag drop clearly doesn't work. They don't do this, but instead tap some keys and pick up a phone and call someone before telling me I should present myself at the Qantas service desk. Stand in a queue at the service desk operated by a single staff member (it is before 6am) for another 20mins during which my flight has now departed without me 3 minutes early at 5:47am (confirmed via Qantas app data). Service desk staff member has no idea why I've been sent there and appears extremely frustrated that I've been palmed off onto her by the baggage ground staff when she can't help me and has no idea what to suggest beyond "come back again tomorrow".
Flight missed, pay docked (> $800) by employer for "no show" missed flight. Qantas advise employer my fault for not allowing enough time to check in prior to flight. Complaint lodged with Qantas, which is never acknowledged or responded to in any way. Complaint lodged with ACA. Qantas again respond in same way as to employer. Vast quantities of evidence are presented to back the case including photographs of the error messages on the bag drop machine display and proof from the Qantas app they departed the plane 3 minutes early (which would have made all the difference to me making it in time despite the broken bag drop reader). Qantas simply ignore all the evidence and stick to the line that the customer did not leave enough time to check-in.
ACA acknowledge powerless to compel the airline to do anything, so that's the end. Ergo, Qantas and Donald Trump are the same. They can say and claim any garbage they like completely devoid of any truth and get away with it because they're unanswerable to any authority and can do whatever they wish, whenever they wish.
Moral of the story: When you eventually get screwed over by Qantas due in no part to any fault of your own (and you will, it's only a matter of time), don't bother wasting your life by complaining to them or the Airline Customer Advocate. Just book on Virgin instead. There is no point. It's as effective as reasoning with Donald Trump. I wasted 4 months of my life trying to get justice and ultimately got nowhere.