> China's pretty corrupt politically but the social trust is quite high, the highest outside of northern europe as far as I can tell

There are a few reasons for that that I can imagine:

- China is one of very few autocracies that has managed to significantly improve the standard of living of most of its population.

- The public trials and (sometimes) executions of allegedly corrupt individuals might help improve the perception of corruption.

- The same harsh penalties mentioned above might influence people to declare a higher level of social trust than they actually have, even if the poll is supposedly "confidential" and "only for scientific purposes".

>The same harsh penalties mentioned above might influence people to declare a higher level of social trust than they actually have.

This 100%.

Political imprisonment and reeducation camps are antithetical to any definition of a high trust society that I would subscribe to.