A common myth on smaller jobs is that a SWMS is a big-company thing. It is not. The duty to prepare a SWMS attaches to the work, not the size of the business, and a sole trader is a PCBU with the same obligation as a hundred-person outfit.
The duty follows the work
If your work is one of the 18 high risk construction work categories, a SWMS is required before it starts, whether you are a solo sparky doing a switchboard or a crew of twenty. There is no small-business exemption.
Who asks a sole trader for one
Two people. On a managed site, the principal contractor collects it before you start. On owner-builder and residential jobs with no builder on site, the person most likely to ask is the WHS inspector who turns up after a complaint or an incident.
The practical problem
Writing a compliant SWMS from a blank template takes a couple of hours per activity once you factor in finding the right citations and getting the controls right. For a sole trader billing by the hour, that is real money, which is exactly the gap a generator fills.
The fast path
Check whether your job needs a SWMS, then generate one for A$39, or grab the whole trade pack so you are covered for every activity you do.