I came across a really interesting Reddit thread today.
(1) India is a low trust country, but we aren't even aware of it. : india (reddit.com)
It lists various reasons why India is in low-trust equilibrium. It made me wonder if the U.S. was heading in that direction, or other countries, or the world, for that matter.
Social capital seems to be a central factor in peoples' well-being in a country, regardless of wealth or advancement. I'm sure that there's other factors and maybe social capital is more of a dependent variable in service to some larger picture, but ceteris paribus it seems to strongly correlate with lower crime and healthier institutions.
I think social capital is one of those things that affects individuals strongly -- it reflects on their attitude and expectations about how others will behave. People from low-trust countries such as India will literally trust strangers much less than people, say, from Denmark.