Final answer:
Motorcycles are harder to see than cars primarily due to their smaller profile, which offers a smaller visual target compared to the larger frontal area of a car.
Step-by-step explanation:
Motorcycles are harder to see than cars because they have a smaller profile. Unlike cars, motorcycles present a much narrower frontal area, making them less visible to other drivers on the road, especially when there is a busy visual environment or poor lighting conditions. The other options listed such as motorcycles being much faster, most motorcyclists riding at night, or motorcyclists wearing helmets do not inherently make motorcycles less visible.