That's pretty common ... the photographer is the director of the shoot ... not the model. It's her job to do what she is directed to do.
Sometimes photographers let the model do their own thing, but almost all of the time they direct them and only let the model move in slight increments... trying out different head tilts, for example, moving their eyes, or hands slightly. It can be slightly colaborative, but it's the photographer who makes the decision when to open the shutter at the right moment. And it's the photographer who is critiqued when the photo is good ... or bad.
A good model can figure out what the photographer wants and can bring his vision to be shot.