The test is not that good. The window of incubation is large. If you test negative you may either be falsely negative or haven’t had time to develop symptoms. Most people that are exposed develop symptoms in a few days but there are instances in which people don’t test positive for 11-14 days.
For the record I have been professionally dealing with this mess since mid March. The testing is a pain. The medical community is uncertain of many aspects of this disease and the recommendations for everything change constantly. In March we were told early intubation was helpful, and non invasive support was not likely to help people with severe disease. Now we know that is not entirely accurate. We were told surfaces were a legitimate risk, then they weren’t, now it is we are not sure. The number of hospitalizations is going back up even where I am (Louisiana) after we weathered the initial surge. The number of cases in Houston is high enough pediatricians are being asked to care for adults.
I am not saying that the vast majority of people infected will not recover. It is obvious now most will. I am not saying we should shut everything back down. I am merely saying it is a complicated problem Because of the disease itself and the limitations of our knowledge. The potential for overwhelming the system is there (at least in some areas). No matter what we do people will die from this, and if we take more drastic economic actions people will suffer/die from that as well.