1. Trains run through very long multi jurisdictional route often with no meaningful police along the routes and no access due to lack of roads along the route. This was especially true historically but still remains true today. Train robberies have been a real thing for a long time with the robbers not being stupid and attacking the train far from police presence. Further rail facilities require 24x7 protection that local police can’t afford to offer.

2. They often have specific laws at a federal level and as I understand it wouldn’t depend on general local courts and prosecutors, particularly on interstate lines. For spur lines it’ll usually be state prosecutors.

The crux of it is the rail companies probably don’t WANT to hire police if they absolutely can avoid it. That’s very expensive and I’m sure they would rather just eat losses, pay insurance premiums, and whine to local and state police for more coverage at the tax payers expense.