With all due respect blabley, how many shortlines have you called and discussed the RRB contributions? Have you called the toll-free RRB customer service number and verified that all short lines and Class 2 & 3 RR's contribute to RRB? What RR do you work for by chance?
This is getting silly, isn't it...
If my citation from the Railroad Retirement Act itself isn't persuasive, then all I can do is to once again urge you contact the Board directly. I'm not equivocating here. Simply put, if a railroad has common carrier obligations, it MUST cover its employees under Railroad Retirement. It is not a matter of choice.
And yes, I do work in the industry, and have done so for over 40 years.