Re: In the interim, the British government has been forced to adopt human-powered contact tracing
> Some people don't have smart phones.
As far as I can tell this is pretty rare (I myself do not own a smartphone). People who do not have one are most often very old people who are not likely out in the street. IIRC the owner rate if 95 percent in the "not a small child and not yet retired" bracket.
The problem is *much* more in the installation numbers. Still, even a non-perfect percentage will lead to alarms when the virus hits those with the app. 30 million (or even more installs) would be great to have.