They have, informally. There is a huge demographic of people in every major city who have never/rarely signed a lease, but simply sublet a room from an official

They have, informally. There is a huge demographic of people in every major city who have never/rarely signed a lease, but simply sublet a room from an official lease-holder, often against the actual terms of the lease. These people generally tend to file taxes as individual households, despite all sharing what is statistically a single unit of housing. I wonder how this plays with the data in the article.