I'm not sure it's just about trust. In a couple of the "high trust" countries you named, there is swift and severe punishment for littering and stealing. Perhaps the trust is knowing that such behavior has painful repercussions. Also I can't help wonder if the seating you observed in Seattle is residue left from the masking and 6 ft. distancing mandated during Covid when the message was, "your fellow humans are filthy germ-ridden beings and are to be avoided."