The entire point of the Constitution was to not trust each other. We wouldn't even need checks or balances if trust were a reasonable governing philosophy. Nor a Bill of Rights, nor any explicit admonition against slavery.
The reason we need these and many more is that we don't trust each other. And it's wise that we don't.
This doesn't mean trust is bad, only that the founders, rightfully, knew that it leads to complacency.
What's landed us where we are is not a lack of trust. (We've lacked trust from day one, that's how we got the Constitution in the first place). What's landed us here is complacency.
It's distrust - in foreigners, in each other - that got extremists elected, and it's distrust - in the media, in the institutions - that gives them unchecked power to destroy the country.
None of which would have happened if we had not gotten so complacent about defending our democracy through vigorous enforcement of the Constitution, and voting in a fashion more informed by wisdom than emotion.
At the root of all you lament is not lack of trust, it is complacency. Decades long complacency.
Lack of trust is what our republic was founded on, and the entire reason it was structured the way it was. Our republic is specifically designed to function in a trust-free environment.
But no republic, nor any other organizational construct, no matter how well designed, will survive complacency.