I would probably err on the side of making it opt-out and not mandatory. You’ve got a valid and interesting question, but my comment was in response to Schneier

I would probably err on the side of making it opt-out and not mandatory. You’ve got a valid and interesting question, but my comment was in response to Schneier’s claim that contract tracking apps are “useless”. > What use would a tracing app have if anyone could ignore alerts at will, because s/he has no symptoms and is afraid of job loss if quarantining? I think this is another example where things are a bit too binary. If anyone could ignore the alert, then some probably will and the rest won’t. The fact that the rest are taking this seriously still helps to avoid some number of transmissions.