It is tempting to treat the SWMS as paperwork you can sort out later. Then the work starts, something goes wrong, and "later" becomes a problem with real consequences. Here is what actually happens when there is no SWMS for high risk construction work.
The regulator
Carrying out high risk construction work without a SWMS is a breach of the WHS Regulations. Inspectors ask for the SWMS first on any high risk work visit, and they can issue improvement or prohibition notices on the spot. Where the failure is serious or someone is hurt, it becomes a prosecution, and the fines run into the hundreds of thousands for a business, far more where there is a serious injury or a death. Real cases are decided every year off the back of a missing or inadequate SWMS.
The builder (the faster consequence)
Long before the regulator turns up, there is the principal contractor. Their own duties depend on collecting your SWMS, so no SWMS means no site access. Your crew stands around, the day is lost, and the builder remembers which subbie held up the job. This is the consequence most trades actually feel: not a courtroom, a locked gate.
The incident nobody planned for
The reason the law is strict is that high risk construction work is where people get killed. A SWMS is the moment you think through the hazards and controls before the work, not after. Skipping it does not just risk a fine; it removes the step designed to stop the incident.
The easy version
None of this is hard to avoid. Check whether your job needs a SWMS in thirty seconds, and if it does, generate a site-specific one in about ten minutes for A$39. That is a lot cheaper than a lost day, let alone a prosecution.