Final answer:
Never drive alongside a motorcycle in the same lane primarily because it's illegal and unsafe, as motorcycles need the full lane width to operate and sharing the lane could lead to accidents.
Step-by-step explanation:
You should never drive alongside a motorcycle in the same lane because it's illegal to do so and also unsafe. Motorcycles require the full width of a lane to operate safely. Driving alongside a motorcycle in the same lane is not only dangerous but also disregards the motorcyclist's right to use the lane. This could lead to accidents and is considered a traffic violation in many areas. Additionally, while motorcycles do have blind spots, instability, and speed differential with cars, the primary reason not to share the lane is the legal and safety aspect.