The short answer?
For civil liability-
If you set a fire from your BBQ and they found you only had some D&RGW books to your name, it's not worth the time to sue you.
If you're a railroad and you cause a fire, you clearly have more money than the D&RGW fan with the BBQ and no appreciable assets. It'd be worth the while to come after your RR in court.
it's really that easy.
For criminal responsibility-
I don't have a clue, check the laws in CO and NM states
-Lee
Flickr photo set of my On30 layout