Plastic barriers are to prevent loss of life while also providing visible safety. That is why barrels of sand / water are used as well on highway areas. The alternative in "teaching someone to drive" is killing them if there is operator error or a mechanical failure. It is designed to fail, much in the way that your bumper is designed to absorb shock and reduce damage to the frame.

Comments update: 14-00290568-Roadway Marking Maintenance
203 K Street Northeast, Washington, DC 20002, USA
This issue has an image. You can view it here http://seeclickfix.com/issues/1323794 . Reflective guard rail is broken AGAIN! Intersection of K