It is my understanding that the church is sort of a cult, and it's followers hide their membership.
This illustrates the challenge with tracing approaches: if people are not open, or not sufficiently aware of the consequences of their actions, it's very easy to miss infections.
The supermarket is not necessarily an optional trip. People have to eat, and if they're not eating in cafes, they're going to get their food at the market.
For clarification, I went to the supermarket myself precisely because of the point you raised. My argument was more against the behavior that people display.
