I see a lot people saying they'd call in the National Guard to arrest the strikers if they did go on strike.

That is predicated on the idea that if you stike, you have to go to a central area with placards and show your displeasure.

The RR Unions could just as easily call a strike and tell people to stay home. This would hobble the Feds response to the strike by noting being able to round up people as a group and forcing them back to work.

The Feds would have to request the help of local police and then basically go to each and every RR Worker's home and try to arrest them. In some localities, the police just might tell the Feds no. It also would require that an arrest warrant be issued for each and everyone one of them. That's what 70k+ warrants. Because you can't do a group warrant, it has to be specific to that person. That's why strike breakers like when they strike in front of the building, you can nab them for disorderly conduct, trespassing or something else, no fuss no muss.

It'd be a PR nightmare. Can you imagine all the cell phone videos of the violent and non-violent arrests of RR workers in their homes when they hit local and national TV?