There is more than one such picture for each of these "stars", wherein he/she is covering an eye. Some performers have been duped into posing as such, but I don't believe that the three depicted here have been duped, but are part of the conspiracy.
You don't necessarily have to be "in on it", just willing to go along with the game in order to get the gig. Likely, though, the photographers chosen to do a lot this type of work are "in on it". Can't say the industry, in general, either, as far too many photographers are struggling to make in a living within that industry alone.