This is purely hypothetical and I advocate the importance of buying train tickets to fair dodgers. This thought occurred to me today:
Imagine I wanted to travel from Sheffield to Oxford by train. The standard off peak price for a return is £78.80 which to most people is a lot of money for a day trip to Oxford to see friends/family back at home. Now Oxford train station has ticket barriers whereas Sheffield doesn't for two reasons. 1) The train station is a grade 1 listed building 2) There is a walkway which the general public use that links Sheffield Station to an independent tram line and public footpath. It is only possible to access the tram line and footpath by walking on a bridge over the station platforms. Given that train travellers and non-train travellers both use this bridge, it would be impossible to implement ticket barriers at Sheffield Station and a recent government proposal was rejected because the station is a listed building.
Now there is a train which goes via Sheffield to Oxford. The crucial thing is that for this plan to work, the train mustn't begin in Sheffield. This is to avoid everyone on the train having to show their tickets for inspection. My friend has travelled between York (another station close to Sheffield also without ticket barriers) for over one year without purchasing a ticket. This is because the train originated in say Newcastle and has stopped at say 3 or 4 station before arriving at York. So when the inspector asks for tickets from York please, my friend sits back and the inspector walks straight past because his assumption is: He probably got on before York. Now the inspector cannot monitor everyone on the train especially at peak times when there's a lot of passenger congestion. The inspector can only ask for everyone's ticket after the station of origin. After that, the inspector relies on you to bee honest and show your ticket.
This is where the term fare dodger comes from. Fare dodgers are people who take advantage of flawed security measures like the absence of ticket barriers at stations.
So going back to my trip from Sheffield to Oxford. Oxford has ticket barriers which means I have to insert a valid ticket into them to pass. They are monitored by CCTV and station personal at all times. You cannot climb over the barriers because station security are standing and looking at all times. Now this train I get on at Sheffield will have originated in Newcastle. It will have stopped at 3/4 stations on arriving in Sheffield. Now this is where the fraud comes in: Given that I must purchase a ticket in order to pass the barriers at Oxford, it could be possible to purchase a return ticket from Banbury to Oxford. Now Banbury is one station away from Oxford and my train always stops there. Compare the prices: It costs £78.80 from Sheffield to Oxford. It costs £6.00 from Banbury to Oxford (both return tickets on the same day).
Theoretically I could board the train at Sheffield and sit there holding a pre purchased ticket from Banbury to Oxford costing only £6.00 because the inspector will have already assumed I'd boarded at one of the stations prior to Sheffield. So I sit on the train and travel about 2 hours to Oxford without a normal ticket inspection. HOWEVER:
The inspector sometimes asks all passengers on board to show their train tickets. Now this has never happened to my friend aka 'the fare dodger' from York to Sheffield. The train also stops at Doncaster and possibly Leeds in between so this just works in my friend's favour. Given that the journey time from Sheffield to Oxford is around 2 hours, there is a strong possibility that the inspector will ask for all passengers to show their tickets. The normal thing for him to do would be to ask for your ticket after each station as I've explained.
Now if he asks this then there's nothing I can do but pay 'some' fare. The amount of fare I have to pay depends on at which time in the journey he asks to see all tickets. If he asks towards the end of the journey, then I can convince him that I boarded at the last station but [lost my tickets via some unfortunate event]. So even then I beat the system and avoid paying the full £78.80 BUT this whole plan is very risky. Should he ask towards the beginning of the journey RELATIVE TO ME. The train had originated in Newcastle and so my beginning is obviously going to be different to the inspector's begging. Even so, if he asks to see all tickets 2 stations after Sheffield at Birmingham then I'd have to pay a pretty hefty price from Birmingham to Oxford.
Do you understand what I'm trying to explain here about fare dodging big prices PROVIDED the train does not originate from the station at which you board.