Sometimes, even with the best efforts, that picture just didn’t go as perfect as the photographer intended. Or maybe the reality is just boring. Anyway, photo manipulation is not hard to find nowadays. For enhancement or correction, or maybe in order to create an illusion or deception for the viewer.
Long before computers photos have been manipulated. With retouching ink, paint, double-exposure, piecing photos or negatives together in the darkroom, or scratching Polaroids. Maybe it is just taking some kilos off the model, or making someone disappear completely.