‘Wearing a mask while indoors in public places and maintaining >6 feet of distance between individuals from different households is a reasonable way to reduce the risk of transmission...’
is it your belief that unmasked people passing each other in a public place without stopping are going to pass infection between them...? based merely on normal, non exaggerated inhalations from the nostrils...?
if so, then why does the covid test require a thrust into the nasal passage to capture enough material to formulate a diagnosis? for that matter, if this is such a virulent pathogen, why do we need to be tested to determine whether we have it nor not...?
Based on the studies I've read, length of exposure is a significant component of transmission risk, so in the specific scenario described, that's probably pretty low risk. However, there are two caveats to that. First, there appear to be some individuals who are vastly more effective at transmitting than others and there hasn't been any information to date on how to spot such persons. They seem to be a significant risk in virtually any indoor situation. The other caveat is the pooled risk that comes with something like a grocery store or a shopping mall. Each individual you pass in that situation may have a low risk for transmission, but so many are being passed that the overall risk of transmission within that population is high. The risk is also there that during the infected person's time spent in a place like a grocery store or a shopping mall, they may be speaking, clearing their throat, or have a random cough or sneeze - even if unrelated to their infection.
"why does the covid test require a thrust into the nasal passage to capture enough material to formulate a diagnosis?"
Because that's how one particular test was created. Others use saliva (such as this one). Others use blood samples (such as this one.) The US just largely standardized on one particular test type that uses nasal swabs. Others exist.
"if this is such a virulent pathogen, why do we need to be tested to determine whether we have it nor not...?"
Because around 40% of people who have it show no symptoms and another 40% show mild to moderate symptoms which may be confused with a cold, flu, or allergies. The point of testing them is so that if they're infected, they know not to visit grandma in the nursing home because that could kill people. For that matter, they should be self-quarantining entirely since plenty of people with comorbidities (e.g. diabetes, obesity, etc.) still need to access public places such as grocery stores. It's a lot easier to identify the ~1% or less of the country with an active infection and have them take steps to protect themselves than to tell ~50% of the country living with risk factors that they have to stay home indefinitely.