In reality TV, there is no script, but there certainly is a guideline. And in some cases, a plot.
Most reality game shows are different (Survivor, Top Chef, Project Runway, Amazing Race, American Idol, etc.). But even with those, the Producers still mold the show as it plays out, to create drama. And while they cannot plan who wins, they definitely shape out who the finalists will be. For instance, if it is a show where the home viewer gets to vote as to who stays, the producer can choose for the most "dramatic" contestant to get more airtime than others. Or edit their interviews to be more likable.
Shows like Duck Dynasty, Storage Wars, My Sweet 16, Jersey Shore, and Cake Boss are heavily shaped. My friend worked on a show that went on Cake Boss. The Cake Boss production company made a contract with the show ahead of time, told us when our appointment at the store would be, and asked what the event was and what they wanted the cake to be. This way, when they showed up to the consultation, Buddy had already known who was coming and what the event was, so he already had thoughts about the cake's design for the meeting. (He doesn't think up the ideas for the cakes on the spot. Who'd a thunk it?) The taped consultation was about a month before the event, so all the scenes where they built the cake were filmed over a long timespan, I guess.
"The Spectacle has, indeed, an emotional attraction of its own, but, of all the parts, it is the least artistic, and connected least with the art of poetry. For the power of Tragedy, we may be sure, is felt even apart from representation and actors. Besides, the production of spectacular effects depends more on the art of the stage machinist than on that of the poet."
--Aristotle