And with regard to the similar thing done by Northern for fares, we have a legal structure with passenger protection for performing "out of court settlements" for unpaid fares. It's called Penalty Fares, and as I've said before Northern should implement those, and should prosecute those who are deliberately evading fares under RoRA thus ensuring the appropriate criminal record. No need for the 80 quid nonsense whatsoever.
This can not apply to the vast majority of
Nothern's lines and services due to the added infrastructure that this would entail.
Northern's options are 1) accept the revenue loss or 2) prosecute all passengers found
sans billet who had a prior opportunity to pay. Neither of these options are really acceptable. The courts are choked already with cases and if a way to reduce the burden of them can be found then that is to the good.
Northern's system offers offenders a chance to dispose of their obligations without the stress of a court appearance by paying an administrative penalty, and the scheme is fully supported by the DfT. As to why there is not a right to appeal, that is also glaringly obvious, as you do not have to accept the penalty but can have your day in court if so desired. There is also another way to avoid this hassle - buy a bloody ticket before getting on the train (usual caveats apply), and failing that if you are in a genuine hurry ask the guard (every
Northern train has one

) if you can purchase on board.
Northern also have an obligation to ensure that booking offices are staffed as required and that where guards struggle to collect revenue on "pay trains" that they are fully supported with ATEs or the equivalent.
NB I do acknowledge that sometimes there are no doubt failings in the application of the system, that does not, however, mean that the system in itself is a failure. I genuinely believe that this system is more about re-educating the travelling public than a mere money making scheme.
Must I disembark with my luggage from the 150/1 and move to the 153 in rear where the guard is located? 150/1+153 is a regular combination in my part of the world, serving many stations with no facilities.
No, but why not (usual caveats apply), if you know you require a ticket, board in the part of the train with the guard. I'm sure that on the first "pay train" line (somewhere in East Angular?) there where instructions to that very effect i.e. passengers without tickets
had to board the centre coach (I assume a three car DMU), where seats were set aside for them. After they had purchased tickets they were free to sit where they liked.