Why should a PhD work at a training centre in China?
First,he cannot get a post in tertiary education in his homeland.Competition is fierce for such jobs as PhD holders are by no means in short supply.
Second,said academic cannot apply for a post in primary or secondary education as he has no postgraduate teacher-training certificate.(Most PhD's have first degrees such as an MA or a BA or a BSc,not a BEd)
Third,many state-run Chinese schools,colleges and universities do not wish to employ foreign PhD's because they are bound legally to pay them high salaries.
Fourth,training centres pay higher than average salaries in China.
That said,in the UK,it's not uncommon for PhD's to be unemployed.Some are either too highly qualified for certain kinds of jobs,or what they have studied is not job-related.I suspect the same applies in other Western countries.