Comments
Two factors to consider here are (1) ingroup circle and (2) shared values.
When someone is seen as part of the outgroup, that someone may not be granted inherent value. As a result, dealings with them may be viewed as strictly for business. Depending on moral framework, the only non-business consideration may be emotional empathy, which of course is not universal -- especially not for members of the outgroup.
If someone's values are believed to be fundamentally aligned with one's own, then likely there will be more automatic trust. But if we look both within and between many modern societies, substantially and inherently incompatible value sets are readily found. Compare for example Christian fundamentalist versus progressivist views on abortion or LGBTQ+. Some societies, such as perhaps Japan, may have relatively more consistent values across society. This tends to lead to greater trust, or at least greater predictability. Naturally, however, there are potential problems if society becomes too monoculture, such as closed-mindedness and tyranny of the majority.
Trust is a natural effect of one's assessment or perception of ingroup-outgroup status and sharing of values. Trying to modify the effect without understanding or addressing the cause is asking for trouble -- and is likely futile. This type of predicament is often referred to as bypassing, in that it bypasses the cause, instead trying to force the desirable effect.
Increasing trust without trustworthiness seems like a recipe for being taken advantage of; increasing trustworthiness (e.g. by punishing low-level antisocial behaviour) seems like the relevant target.
Related, I'm a fan of the term "justified trust" here. A wrote a bit more here.
Increasing justified trust seems great, but increasing unjustified trust is hazardous. (My guess is that the OP is mainly referring to justified trust, but it seems good to clarify)
Yeah I think this is a distinction where everyone agrees when the distinction is raised but attempting to do policymaking without the distinction front of mind can lead to accidentally aiming for the wrong thing. Thanks for re-sharing the link!