We're going round and round in circles!
...There are a significant number of frequent travellers who know all this and play it to their advantage. Obtain a promise to pay ticket, or take a timed photo of an out of order machine, or of the long queue preventing them from getting a ticket...
If a passenger is unable to purchase their required ticket using their chosen payment method, because cash is not accepted, or the machine is out of order, they are entitled to board the train. A long queue can be a grey area; some train companies give clearer guidelines than others regarding acceptable maximum waiting times.
I fail to see how passengers can be 'blamed' for any of these things.
Northern specifcally state, in their Passengers Charter that...
...the ticket machine at the station is card only and you wish to use cash, then you should obtain a promise to pay ticket from the machine and pay at the first available opportunity....
No other train company asks passengers to obtain a "promise to pay" and there can be no legal basis for Northern to require passengers to obtain one, however doing so does demonstrate without any doubt that you were unable to buy the ticket from the machine and confirms the boarding station.
I understand you are unhappy that cash is a valid payment method; feel free to lobby your MP to remove this option if you want, but it aint happening!
In the meantime, complaining about the fact that people can use cash isn't going to change anything.
Oh no, I fully appreciate what a Promise to Pay is all about. There are two reasons to get one from the ticket machine rather than a ticket. Firstly, there is the 'correct ' reason, where you want/need to pay cash or buy a ticket not available, and therefore need to buy your ticket later - rock up at Leeds without one and ask to buy a ticket, and there is every chance you'll be stung rather than being sold the ticket you are asking to buy. Secondly, as I described in my previous post, they are a risk free way of not paying when travelling to a station without barriers.
I don't understand what you mean; a promise to pay is only available from machines that do not accept cash; the holder of such a promise to pay is promising to pay in cash. I don't understand what your 'second' point means.
I'll also add that there isn't anything in law that compels passengers to obtain a promise to pay, so if the passenger arrives at Leeds and asks for a ticket from an unstaffed station, there is no legal basis to prosecute or penalise a passenger who does not produce a 'promise to pay'.