a proposal in a comic-book format for a privacy friendly contact-tracing that is effective to boot. Go to that link and read the entire post carefully. It has been created with the help of privacy experts.
Apple and Google announced a joint-effort to provide APIs that will enable developers to make privacy-friendly contact-tracing apps.
There are many arguments against such a contact-tracing technology (no technology is perfect):
it is not accurate (it is better than nothing – even a certain percentage of false-positives might be acceptable in the absence of anything)
if a person self-reports, she may be penalized by the authorities (that is a fault of the authorities, not of the technology). In any case, any behavior or outcome that discourages self-reporting only exacerbates the problem by hiding it and making it into a worse time-bomb
the person will lose her privacy because her neighbors will find out and ostracize her (nope, the proposed technology makes sure to protect the privacy of all involved individuals)
And many more arguments, many of them justifiable. But not doing anything is not justifiable at all. These are unprecedented times. The choice is to have a lockdown and kill the economy, and mainly the poor people and service-sector with it. Or to identify the newly-symptomatic and asymptomatic potentials and provide them with immediate care and quarantine so that infection and spread are nipped in the bud.
There were similar arguments against masks (they are not good enough, droplets can get through anyway) but again, something is (almost) always better than nothing.
Public Service Announcement: Practice safe treks, wear a mask when you go out.