what is the current understanding on the viral spread because from what I understand it would be very hard to transmit between two unmasked people passing by outside
So I think this is where a huge failure occurred that was an indirect consequence from lack of leadership and proper messaging. When the pandemic first started there was nobody telling anyone what the proper thing to do was, hell there still isn't really. The only thing you got was oh things are fine its not that bad from the administration and then what people saw with their eyes and the reality of the situation was not good. Additionally, you then had conflicting messaging because of politics.
What ended up happening was people did the normal thing where they looked to reaffirm something they already believed, super cautious or super reckless. People also started to do their own "research" as well as the media looking for any information they could get, including deep diving into non-reviewed scientific articles, random "experts", and a whole bunch of unfiltered complicated things were disseminated to the public. For example, the original study that showed that the virus was found on different surfaces for ridiculously long times, like days. That study was real, the science was real, the group was NIH and collaborators, the results didn't mean what people thought they meant. Result the public took away, people are spraying down their groceries with disinfectant and leaving packages out in the sun for an RNA virus.
It also wasn't just the public, because the virus was new and had such a spotlight on it scientists decided that all previous virology and immunology knowledge apparently should just be forgotten and everything had to be reinvented, then after the studies were done surprise surprise it acted like a virus. For example like it was some earth shattering finding that duration of illness, level of sickness, and course of infection is tied to initial viral load. With all that said, and it may be too late with credibility just shot, there should be public messaging everyday about the realities of the virus and what to do.
Anyways personal opinion on messaging should be that face mask coverings should be required whenever indoors, additionally facemask coverings should be required when outdoors in a crowd of people greater than 5 that can not maintain 6 feet distancing and the time in said crowd will exceed a short period of time. The mask at a gas pump, unnecessary, mask while on a trail unnecessary, mask while sitting next to someone on a scenic hayride to the apple orchard, necessary.