We don't have extensive contact tracing. I've never once engaged with a contact tracing application, nor anybody that I know. You failed to answer my previous

We don't have extensive contact tracing. I've never once engaged with a contact tracing application, nor anybody that I know. You failed to answer my previous question: is it impossible to extrapolate knowledge of how the virus spreads, to judge risk of various scenarios? Do you require evidence from every permutation of possible activity?