Great post for the general public.
The challenge is when there are health care facilities or other important areas.
It would be better if only folks who tested negative were allowed in those facilities.
For now that is crazy wishful thinking—but we may get there.
Good example of what happens when we cannot test first:
11 residents of a nursing home in Troy, Ohio have tested positive for coronavirus
In addition, 3 residents and 2 staff are hospitalized and awaiting test results
https://twitter.com/lookner/status/1241078410773958656