Why should you not share lanes with other vehicles?

• By driving close to other vehicles, one can remain safe in the company of the rest of the traffic and hence lane sharing is good.
• Lane sharing is useful because 2 vehicles will receive more notice than 1 and hence it is safer.
• By driving too close to other vehicles, motorcyclists are at a risk of collisions and accidents and hence sharing lanes should be avoided.
  Explanation:

  "By driving too close to other vehicles, motorcyclists are at a risk of collisions and accidents and hence sharing lanes should be avoided."
• Both the second and the third statement are correct.