I have no idea how you come to that conclusion.
Well, the thing is, when a passenger does something wrong, the rail industry has managed to convince Parliament that proving intent would be too difficult and, consequently, we have strict liability offences under the byelaws. In effect, this means dishonest intent on the part of the passenger is very often simply assumed.
Now, where a TOC is overcharging passengers, the nub of the difference between your attitude and mine may well be that I believe, almost on a point of principle, that TOCs ought not to be able to rely on an automatic assumption that the overcharging is unintentional.
For the record in this particular case, I believe it's unintentional. The mere fact that tickets continued to be sold at the wrong price for months after a round of fare increases from London Underground TVMs shows that the failure to resolve issues with TVMs can occur in situations of undercharging as well as overcharging, so cannot always be intentional. On the other hand when I look at the range of tickets available at the TVMs at Heathrow Airport, I absolutely believe the overcharging is intentional, because the failure to offer the best value fares is quite systematic and can only really be the result of a special effort.
But in order to make my point I'm not relying on anyone agreeing with what I believe regarding intent in this or any other case. I am saying that intent to overcharge ought to be assumed purely because overcharging is the inevitable consequence of failing to display the cheapest fare, and the regulator should respond accordingly, with fines etc. (I am aware that this would involve introducing an effective system of regulation and giving the regulator the relevant powers, so couldn't be done under the current arrangements).
I'm sure the way the TOCs view this kind of issue is to a large extent a function of the way the regulator views it. I just happen to believe a much, much stricter and dimmer view of it ought to be taken, and if it were, the urgency of the response and the resources that would be made available to prevent it happening, and to fix it when it happens, would be different.