To get an idea of what specialists/GPs earn, the medicare rebates are freely available on this Health Dept. Website (use the 75% rebate fee):
https://www9.health.gov.au/mbs/search.cfm
Practice costs for a solo practitioner can be around $10,000-$15,000 per month. (ie room rents, secretaries etc). Medical indemnity insurance is highly variable, eg. a gastroenterologist is around $20,000 per year. Anaesthetists tend to have much lower overheads because they are in much larger groups eg. 10-15, so sharing costs of secretaries/rent/billing costs can work out around $3,000 per month. They don't need expensive equipment or flash rooms similar to GPs or specialists as their offices are mainly billing rooms and occasionally patients will come in for a pre-op consult. Insurance for anaesthetists is around $8,000-$10,000 per year.
Compared to working in private, a specialist (regardless of specialty), at least in Qld, earns a minimum of around $250,000 + overtime
https://www.health.qld.gov.au/medical/packages/Staff_Sp.pdf . 5 weeks annual leave + super + 2 weeks conference leave + salary sacrifice.
A private health fund pays more to the doctor than the medicare rebates. These schedules are freely available too on respective health fund websites. Now, most specialists charge over what a health fund rebates (ie a gap), so their earnings are well above what is estimated from medicare rebates or health fund rebates.
eg. gastroenterologist doing 17 colonoscopies in a day (15- 20 minute procedure) = item # 32093 = $5525 (bulk billing fee). MBF no gap fee is $561/colonoscopy = $ $9537. Of course, some patients have a combined gastroscopy / colonoscopy, and some have a gastroscopy without a colonoscopy etc. These fees are without gaps. If you do two different procedures at the one time, you get paid 100% of fee for the highest item, 50% of the second item, 25% of the fee for the third procedure etc.
eg. ENT surgeon removing tonsils in 10 patients in a day = (30 minute procedure) = item # 41789 - Bulk bill rate - $204. MBF rate $427
eg. Anaesthetist are renumerated slightly differently from medicare/health funds. they are paid for type of procedure (based on difficulty) as well as length of procedure (to compensate for slow surgeons). eg. doing 5 knee arthroscopies in a morning on an orthopaedic list = item 17610 (pre op consult), 21382 (knee arthroscopy), 23033 (time 40-45 minutes) = $182 bulk billing fee / $305 MBF fee. Few anaesthetist do not charge a gap. They spend the majority of their working week in the operating theater so are always doing "procedures" ie. anaesthetising rather than "in-room consults" like other specialists.
Generally, the longer, more complex operations don't compensate in remuneration for shorter quick procedures, eg. doing one major complex bowel resection in a morning isn't as financially benficial compared to doing 4 laparoscopic cholecystecomies in that morning.
hope this helps!