I didn't mean to imply otherwise. Perhaps I should have re-worded to:- it's on the railway, so railway law should be applied.
That's not how it works. The railway has Byelaws (and other things like RoRA) to deal with situations specific to the railway that other laws don't cover, such as fare-dodging, which may be considered theft of a journey but actually isn't as you aren't taking something with a permanent intent to deprive. It doesn't need its own murder law, nor assault, nor public order offences etc. The ones that apply everywhere else are quite adequate.