If you can be trusted to do the right thing — that is, report a positive result to relevant health authorities so they can do contact tracing, and self-quaranti

If you can be trusted to do the right thing — that is, report a positive result to relevant health authorities so they can do contact tracing, and self-quarantine for the duration of your illness — then having it automatically reported for you is a useful convenience. If you can't be trusted to do the right thing — that is, if you're not going to report your positive test result — then automatic reporting is useful for society to handle that case, too. I'm generally against mass data collection, especially from the government. But not in this case. Hiding a positive result is ethically indefensible. Even if you're feeling fine, interacting with you while you're positive may be a death sentence for others.