Many people don’t think of renting out their couch or their car as a form of paid work, so they don’t tell census workers about it, let alone the tax collector.
The obvious thought is that official figures are a bad place to go looking. Not everyone declares gig income, especially if the work is done alongside a traditional job. Many people don’t think of renting out their couch or their car as a form of paid work, so they don’t tell census workers about it, let alone the tax collector.