How do we know who is in a bubble? :) When I walk around downtown, I see hundreds of people on their phones, and maybe one or two of them is actually using it a

How do we know who is in a bubble? :) When I walk around downtown, I see hundreds of people on their phones, and maybe one or two of them is actually using it as a phone. Obviously I don't know if they're on dating apps specifically, but they are enormously popular, so it seems plausible.