I don't wish to belabor this, but the "cannot be fired if you're in a union" myth is simply that, a myth. You cannot be fired, however, simply because the boss doesn't like you, which you can as an "at-will" worker. Management must be able to prove that whatever you have done is a dismissable offense to an unbiased government arbitration panel (state labor board, National RR Adjustment Board, etc.). If the board agrees, you're done. This is called "due process", and it has been place since 1935 (1934 for RR workers). Due process and the fact that a ratified collective bargaining agreement is an enforceable legal document is why companies will spend millions and work so hard to keep unions out -- if their workers are "at will" employees, they can promise them the moon today and fire them all tomorrow, legally.
The U.S.labor movement began in the RR industry and has always been an important part of it, but enthusiasts seldom acknowledge that, one reason why "real" railroaders tend to think lowly of them. I'll bet the bygone brothers on the D&RGW would not think highly of your non-union sympathies. There is a good deal of difference between playing trains on a nice summer day and doing it at 10 below zero.
As one of many who suffered greatly when a scab RAILroad outfit from TEXas (which I won't name) bought our line, I hope I never have to go through it again....