Or like say hey this part in the movie I did not get can you explain it to me. Or ask something about their past or how they feel on being naked in a movie? I mean it would lower the pool of people who would come on, but it would be way better for their jobs showing they can be honest about shit instead of always pushing some crap movie or crap book or crap Broadway play? They always seem to come out years later and say yea that movie sucked it was a shit experience. Then the host could ask why the hell did you pick to do it to begin with?
For the same reason people in infomercials seem to find it so impossible to perform basic human tasks like pouring a drink without a special drink pouring handle. The whole show is staged to get you to buy something, usually a movie ticket or a book. Talk show questions are often given to guests ahead of time to consider answers or given to the host by the guest to make it easier for them to promote their product. Neither of them is speaking as themselves, but as improv actors in an unscripted commercial.