I've been looking at this forum for ages but first time poster.
I'm am a doctor so think I can comment on this thread - at least from my experience.
My base salary when I was an intern was just under $25 an hour. At that time some approx 6yrs ago, a graduate teacher earned more per annum. A friend who was 20, no degree, working at ALDI earned more than I did.
I spent one year working in general practice as a registrar. I would doubt there are many GPs outside of the large bulk billing superclinics who see 50 patients a day and earn the figures China is talking about. As a GP unless you are a partner who has sunk a good deal of capital into a practice you work as a contractor. This means you earn a percentage of billings. As a registrar you earn something like 43-50% of billings, depending on seniority. I was pretty much flogged and saw probably around 30 patients in a day (830-6pm, often working through lunch). Many, many GPs will bulk bill kids, elderly and DSP/unemployed on health care cards, so I think that China's figures are highly inflated and not representative of the majority.
I'm now working in a hospital doing a specialty program. Most programs take a minimum of 6-7 years post intern level. That means study and overtime on top of your day job for that many years. The base salaries go up each year till you reach registrar 4 level (NSW anyway) then plateau until you become a consultant - which involves taking multiple costly exams. Overtime varies depending on specialty, hospital rural vs urban. For most specialties you are required to move around hospitals and usually to a rural area for part of your training. You must belong to your specialty college which will have fees and run courses you have to attend. All that coupled with registration, insurance, exam fees etc could add up to 5-10 thousand spent on training out of your own pocket per year. I would guess most of my colleagues at my level earn between 90,000 - 140,000 depending on how much overtime.
In regards to oncall - as a registrar I do plenty of this. Most times I'm on call I have to go in, most times for many hours - often working 18-24 hours in a row with no break. It's rare for a consultant to come in overnight. I usually just ring them if require advice.
When I am finished as a consultant in the public system I can look forward to a salary of around $180,000. (Thats after 5 yrs of med school and 8 yrs of post med school training). In the private sector rates would be higher but you have to build up your practice.
There are easier ways to make a lot of money. Unless you have a dedication and desire to help people and enjoy health then I reckon you are crazy to do medicine. Money certainly wasn't what I did medicine for and that still is the case. I plan to use property and other options to build wealth.