This isn't random at all, lots of people are staying inside and going out to the store once a week or less, they will be dramatically under tested with this met

This isn't random at all, lots of people are staying inside and going out to the store once a week or less, they will be dramatically under tested with this methodology. Meanwhile other people are going out every day, or they know they previously had covid so they consider themselves exempt from shelter in place, or they have a job that requires them to continue heading out to work despite shelter in place (and therefore they have had far more exposure to covid than average).