[Gibbon1]

From my opinion I'll add two things.

We're expected to interact with people cold. Know nothing about them and have no shared experiences.

We have a culture of fear of strangers.

A lot of this is due to fear mongering by the media and suburbanization.

So you don't live in a small community where everyone knows everyone. You don't live in a dense city where you rub shoulders with lots and lots of strangers who are all okay. You live in a suburb where you never have a detailed interaction with strangers. And the media tries to drive home that those people are dangerous.

One thing that's declined in the US is churches, clubs, neighborhood bars. Which were good ways for people to meet each other in a high trust environment.