Doesn't bluetooth give too many false positives anyway (with its range that is far greater than the required 6ft, and its ability to pierce walls?) And how will the general public respond to these false positives? I fear that the effect of a covid app will be somewhere between chaotic and useless.
The protocols I've seen involve using the signal strength, including knowing the transmission strength, which will probably allow treating people on the other side of any semi-solid wall as "not in contact".
