Until recently, most foreign workers in China had no pension, or other benefits, because they did not contribute a penny towards earning them,.  But they had health insurance. 

Now foreigners do pay Social Security taxes, and are eligible for pension once reaching the proper retirement age, if still in China.  And also many foreigners complain loudly about this, because in their plans, a life in China was just not even consider, so they claim they are paying for something they will never enjoy.  But, also many die before collecting a penny , that is how the system works.

Can you explain what do you consider "social benefits" ?.

No, it doesn't bother me at all....  I guess I'm one of the people Happy is referring to above. I'm only planning to be here year or two, have health insurance through my work contract, and have some pension arrangements in place at home already (although, obviously, not that much since I'm only in my 20s). In my case, the time here is paying off debts and saving to a. volunteer somewhere else for an extended period of time and; b. do a masters degree. 

Some thing that does bother me... I've no intention of ever claiming a Chinese pension, and really don't like the idea that some 40 per cent of my income will be claimed by the government in the name of 'benefits' that neither I nor any westerner I know will ever be able to claim. 

Sorry but I don't have that problem. I'm sure as a ESL teacher that would promote some problems if in China long term, but teachers of subjects and expats at foreign companies generally have everything from 401k to stocks, to international insurance, ticket paid for you entire family and so on