Instead of assuming that someone is well-meaning and requiring much evidence to refute that assumption, people are marked by small infractions, because the cognitive effort of the presumption of innocence cannot be applied on such a large scale and is not worth it to us. This is the mentality behind the "believe all women" principle: women are harmed more by letting a rapist free than by jailing an innocent man, and since we can't vet all the claims of sexual assault, better just lock them all up. A metaphor frequently given by proponents of that ideology is that men are like M&Ms. Would you eat an M&M from a bowl if you knew that a few were poisoned? If even 1 in 100,000 were poisoned, would you take the risk? No. Low trust. (I've never heard someone reply that women are not all benign either and yet people don't seem to apply the same logic to them.)
You see the extremes of this in the politicians representing US political parties. Trump can say anything and supporters never waiver, because they know he's "just joking around" or whatever. Meanwhile a Democrat candidate can say something small askance with what seems to me like innocent intentions, and their career is over.
This is also why the Democrats are so fractious internally, relative to the Republicans. Republicans default to trusting each other (not saying whether that's merited or not) while Democrats only make temporary uneasy alliances.
Some people tire of this low-trust culture (because they haven't been burned by trust before) and are pushing back on it.
In my opinion, the low-trust people are going to win eventually because the higher-trust people are more local and less internet-connected. Either society will collapse into many sub-societies, or else these sub-societies will dwindle until there's nothing left of them, and all that's left is The Culture.