The forum is very Europe focussed. Not many US as options are very limited unless you give up your citizenship. China is a place of its own and they are traditionally very well organised and any loophole is immediately shared somewhere in Chinese.
But what I meant was that the 30 days outside China rule only applies to non-domiciled persons. If you are domiciled in China (hukou), you need to pay tax in any case. The hukou is similar to the residence registration in Europe and also︀ comes with similar tax liabilities.