Not that I would particularly like to live there but Singapore has fairly clean public restrooms. I suspect there is more to this than the ethnic makeup of the country.

In the West, I’d argue (from personal experience) that a high trust society probably correlates more with high level of employment and (maybe as a second order effect) reasonably high income.

Taking Switzerland as an example, it’s possible to have a managed/positive approach to immigration and maintain very high societal standards.

Your bewildering obsession with "populism" sure does define your entire worldview