"A major reason for the strike is job security for union members."

in my eyes - THERE IS NO SUCH THING AS JOB SECURITY!   job security only comes from an individual's singular ability to provide the type of skills needed to accomplish the given task required by an employer at the rate being offered.  as long as that person has the ability to learn and master that particular skill, that person should be the one to get the job at that rate.  

that's where competition comes into play.  and that's what the market place is all about!  if a person can provide that needed skill at a MUTUALLY AGREEABLE RATE between the worker and management, which may or may not be at the going rate OR LESS, that is the point where there might be an employment relationship.  

NOTHING IS GUARANTEED, IN WRITING OR VERBALLY, CONTRACTUALLY OR OTHERWISE.  the person provides the skill needed at the rate being suggested by the employer - and it is not guaranteed!  NO MORE, NO LESS!