I think you are missing the point. This is not an app to determine that you are safe. It is not even an app to determine if you have been exposed. It is an app to notify users that they <em>might</em> have been exposed and should be tested. It is a way of prioritizing who should be tested.
If you live someplace with adequate medical resources, you can get testing when you need it, and the public health system can employ traditional contact tracing for those who test positive to find, test, and isolate as needed.
The app is a supplement to the traditional methods for combating infectious disease that have been used since the late 1800s: diagnosis, isolation, and contact tracing. It was never intended as a substitute.
