because job security is as strong as a thread of cotton!
And this is different than any other job on the international market how? Because if you think that direct employment jobs in the ME or contracts in Japan or Korea are secured jobs, you need to rethink that
China is paying more because as a base is less attractive than other places and they have a need to attract qualified crew members...! Medicals is an issue yes but so it is in Japan and Korea, it isn't as attractive as other places for families but it all depends on which city and what company you work for, I know many guys that has gone there from the ME and are quite happy. It is as simple as a supply and demand issue. And with all things being equal, I'm all for pay parity for Chinese nationals....!
they have the need, it is their train set, so the locals need to be shown the money as well....!