Without jumping into the surprising (but also unsurprising) vitriol that has emerged in this thread, it is possible for the railway to be too strict in some areas and not strict enough in others. And before anyone goes off,
please don't go on about some sort of cultural superiority/inferiority.
British ticketing is complex, we all agree on that, and as with any complex and fragmented system, mistakes are bound to be made all the time - by either the customer or the provider. I myself have, in hindsight, broken some part of the NRCoT or Byelaws at least four times in my time here - all unintentionally, despite taking a much greater amount of interest in transportation and legal matters than your average passenger. You may point out that I am not prosecuted - that is a fair point, although I believe it comes more from a lack of enforcement than leniency on the whole.
This thread refers to penalty fares as a form of leniency. Penalty fare esque systems, with much better appeal mechanisms and less obscure requirements on both the passenger and operator (none of this pay before 21 days nonsense, none of the precise wordings of posters, etc) are
standard across most of Europe and the world. Many of them are framed under byelaws, and are legally classed as an on the spot fine, but the effect is the same as a penalty fare. Pretty much nowhere else in the world will you be asked to pay 2k pounds after using an expired railcard once.
It is also true that on the forum, we suffer from selection bias, because people who have good experiences with the railways don't come on here to talk about it. Of the people who do come here, the vast majority have actually committed fare evasion. They may or may not receive disproportionate or extortionate punishments - and I suspect most serial fare evaders who get an OOC settlement don't feel it is disproportionate compared to the magnitude of the crime they have committed - but they have knowingly committed a crime, and many of them do also seek to hide things even after the fact. It is also true that fare evasion is very, very rife - a disappointing number of people of my age, for example, commit some form of fare evasion (although within my social circles, I have been able to use this forum to demonstrate why it never works out). I spoke with a WM train guard the other day on a late night train, and he expressed the sentiment that he could do nothing about a number of very obvious adults asking for child tickets on board despite boarding from a station with TVMs, because the TOC did not have the manpower and resources to have RPIs, and he was happy "just to get something or anything out of them" every night. A simple headcount showed that WM was likely losing maybe a thousand pounds per night on that train alone. I'm sure many TOC employees on the forum will be able to share similar stories.
On the other hand, just because the system catches mostly thieves and there remains more thieves to be caught does not mean it is automatically correct to catch more thieves. Society does not operate on a linear scale.
There exist miscarriages of justice. Many guards, RPIs or even entire prosecutions departments appear to be poorly trained, and they let off the wrong people
and go after the wrong people. We've had discussions before about how violent or intimidating individuals will be able to get away while vulnerable groups are more susceptible to be checked. TOC staff, like all humans, suffer from implicit bias - I've had ticketline staff stare at my rover for a full minute while absentmindedly letting several respectable suit-wearing white men through the barrier without even checking their tickets, then asking "how did you find out how to buy rovers?" - and even when caught, rich fare evaders (undoubtedly the kind that needs the strongest penalties as deterrent) can be confident of an out of court settlement, with lawyers to help them with gaps in knowledge when necessary, even when the fare evasion is industrial. I suspect many poorer people will not realise what is going on, get thrown in a panic at the scary big number, and plead "take pity" to the courts. That's the first reaction of many forum posters as well. Tourists and immigrants are most often caught out, and their behaviour annoyingly often matches that of the typical industrial fare evader - feigning ignorance, weird addresses, lack of willingness to interact with TOC staff and lack of ability to communicate clearly, etc. Leniencies mentioned upthread, like penalty fares (if that could even be considered a leniency), forgotten railcard policies, and excesses often seem to be applied arbitrarily, with some TOC staff on the forum even explicitly stating that they will not use these "statutory" leniencies (helmet - they will have their own good reasons and frontline experience, but this demonstrates just how non-uniform enforcement is and from the customer point of view can lead to unpleasant surprises). We've had examples of staff, especially contractors, simply being downright wrong, and then the prosecutions department also being wrong.
This does definitely put people off rail travel. It is one of the greatest difficulties I encounter when explaining Britain's rail transport system to immigrant communities - more than off-peak restrictions which LNER thinks so complex, more than split fares and routeing guides, it is the fear that one day they will get on the 1418 on platform 13 rather than the 1419 on platform 14 and get landed with a 150 pound bill that makes immigrants go "nah, I'll take the coach" (especially b/c of their vulnerable status to legal trouble). It is the reason that I always split with flexible fares or even rovers wherever remotely practicable.
There are flaws to the system where enforcement and deterrence is clearly not working. There are also flaws to the system where innocents or the ignorant are punitised heavily, leaving a sense of being ripped off, especially when it is common knowledge that so mnay people get away with fare evasion. Any discussion about fixing the system, and making railway legislation farer, needs to address both issues.