Why might a turn assist system not always detect that a cyclist is present?

You answered correctly. A turn assist system might fail to detect cyclists for several reasons. Dirt on the sensor can block its view, preventing it from identifying cyclists accurately. Parked cars may physically hide cyclists from the sensor’s line of sight, and if the sensor itself is damaged, it might not function properly. It is important for drivers to stay alert and not rely solely on assist systems, especially near intersections or bike lanes, as no technology can provide perfect detection in every situation.