Three words: managment, management, and management! They totally don't know how to ballance their job while mantaining employee morale. They govern in a pseudo-military "do as we say, when we say it" style regardless of the labour laws, collective agreements, or past operating practices. This attitude comes from the top down, starting all the way to the CEO and President, Hunter Harrison. Managers will literally sit in the weeds with binoculars, or treck through the ditch at the side of the tracks just to observe employees and wait for them to do something they don't approve of. And after they observe them they'll come down on them like the Hammer of Thor.
In a skilled job where you're literally paid for what you know and how well you do it, the management wants an ignorant and ill-trained workforce that they can boss around. Senior employees are harrassed to the point that they leave or are fired after 25+ years of service, and junior employees are rushed through training to the point that they don't know even the basics of doing the job. Which may be fine in some circles, but doesn't seem like the best way to run and organization that routinely transports dangerous and toxic chemicals in heavily urbanized areas, using equipment that can easily cause someone to lose a limb or worse.