The Pelican
Member
Perhaps it would be based off "shortest road alternative", although if there was a Severn Ferry, the railway might offer cheaper end-to-end tickets to compete with it.So, Barnstaple to Swansea should be cheaper than either of them to Bristol? There are many such examples.
I think the main point is that, where the railway network is inefficient for a particular journey, the cost of that can either be bourne by the customer (a problem with per-rail-mile pricing) or some sort of system can compensate for it- market-based pricing arguably already does, but "As the crow flies distance" or "Shortest Road distance", or "Shortest Road Travel Time At The Desired Time of Day", would all account for this.
(This is similar to the old BR idea, of a Commercial Speed of 60 MPH)