What you've cited here is an example of how broad generalisations, such as I made, come undone with the odd contextual variable. You're quite right in your position. Earning $1000/day is very different from the Aged Care Assistant situation. Many of these are well-intentioned people with very little basic training in caring for the elderly and frail. They're not trained to observe a person and assess their health status, no training in infection control or barrier nursing etc etc... Their pay is pathetic.
One might infer that the low wages and poor conditions that are applied to casual Assistants and even RNs in Aged Care is actually a feminist issue because the vast majority of nurses and assistants are female. The low rates of pay and casualisation is exploitation of females, and by extension of males too, because they can get away with such standards of employment. When the majority of workers are casual instead of permanent its easy to see that the people are being taken full advantage of the corporate profit incentive rather than provision of service of a professional standard.
You suggest that health care workers "can actually choose to enlist for casual shifts with relevant facilitators...". Yes this may be true for some, but for most its a necessity to fragment their working lives and juggle several different facilities in order to make sufficient for their needs.
But what of professional development? ongoing training and education? what of applying for a loan or mortgage? What of sick leave, which enables sick staff to stay home and recuperate instead of spreading their infection to their colleagues and patients? what of the basic need to have some paid time off work for recreation (annual leave)?
Its all ok for you being paid $1000/day... you can save and take your own time off. the same doesn't apply to those who are underpaid or unable to obtain adequate employment for their needs.
