In my opinion the crew shortage is self manufactured. In light of the PSR related goods shortages, the railroads have been encouraged to hire by the government. They still want to keep the employment levels low, in order to keep with the PSR business model. It seems like the railroads do everything in their power to make railroad employment as inhospitable as they can. This ranges from strict attendance policies, to more efficiency tests. Apparently something like forgetting to say "over" on the 378th. out of 982 radio transmissions on a yard job its to be turned into a major rules violation. Now the locomotives all have inward facing cameras. Say the window vibrates open .5" and your safety glasses are off......major violation.
I live where many comparable jobs exist. I've seen dozens of trainees come and go over the last half dozen years. Maybe the retention rate is higher where the job market doesn't have many good jobs. I also think that the desirable of a high paying job over one with a good work home balance might have something to do with crew shortages. That was a big sticking point in the recent national contract negotiations. The railroads dug their heels in. Maybe they need to realize that fewer are willing to be on call 24/7 isn't as desirable, no matter what pay scale as it used to be.