That all depends on where you are, Turnoi. A friend of mine in Beijing earns about 7000. Month more than I do, but by the time we pay our tax and rent, we have about the same amount each month to live on. Given that prices in my "village" are about 30% of those in Beijing, I am much better off financially than she is, despite the lower salary. Also, by living on my "hustle money" I haven't touched my school salary for over 2 years. Therefore I'm arguably much better off than your cleaning woman, lol.
When you consider that, (in USD), the average annual salary in Qatar is over $146,000, Australia $48,000 and Haiti $1836, everything is relative mate. Earning a Chinese salary and paying Chinese prices is far better than earning an Australian salary and paying Australian prices. Admittedly, the problem only arises when one wants to exchange RMB for the $ or pound, and go back home. Then again, I wouldn't have been able to save money in my home country like I have in China, so your whole point is rhetorical.