As a viewer, not having any clue what’s going to happen next is the draw.
Of course, that’s also the potential danger when you’re making the movie because you never really know how these “normal” people will react.
The rest of the people in the film are just people, who are about to be, largely unknowingly, subjected to Borat’s antics.
What makes Borat movies so hilarious and dramatic is that, usually, Sasha Baron Cohen is the only one in the shot that is aware he’s being filmed for a comedy movie.