It appears that 'truth'is more of a theological matter than a 'scientific' one. Though for me the line between science and theology has dissolved.
And very few humans are truthful. The default state of humanity being one of 'untruth' or 'darkness'.
I believe 'truth' is a set of qualities of a force that is used by an actor/agent to sustain a certain strategy.
Even if all agents could say the truth explicitly, we wouldn't be sure that the outcome would be optimal. Chances are, that life would be impossible and there'd be no human settlement.
If, we are to imagine a world that has an even distribution of 'truth' across its population then that world would have to be a 'post-human' one.