How San Francisco plans to trace every coronavirus case and contact

"But it’s not clear whether a critical mass of the population will ever hear about or choose to download these apps, says Ryan Calo, a University of Washington law professor who focuses on digital privacy issues. If few people enroll themselves in such tracing efforts, it could at least undermine their effectiveness and may even give some users a false sense of confidence about where they can safely go out in public, he says."