To go back to this quote....
... it's too time consuming and costly for minor matters like this...
It isn't.
But predicting the winner isn't always easy.
Example 1
5 years ago a Northern conductor sold a ticket to Burley in Wharfedale, to a person he knew (and perhaps didn't like?), who lived in Burley in Wharfedale. However the conductor later reported that he believed this person got off at the next stop. There was no CCTV, no witnesses, just the guard's word against his. As he was a law student he represented himself. Big mistake as he lost the case. See
Law student gets £1,000 bill
Example 2
At around the same time, a passenger asked for a ticket from Burley Park at Leeds, however as there was a full ticket check there, staff were suspicious and asked for her name and address. She had recently moved from living near Burley Park to living near Headingley (one stop further out) and gave her old address without thinking, they then discovered this was not her present address and prosecuted her for attempting to pay a fare 10p less than was correct. She won the case.
Passenger_innocent_of_10p_fare_dodge
And for those who say it's not worth the TOCs persuing cases like this, that is incorrect because, as far as I know, the cost of bringing about these cases, which were over a few pence, were funded by taxpayers, not the TOCs. So why should Northern decide it's not good value? It's taxpayers money, not their money, that is used. So it's not good advice to say to passengers "don't worry, TOC's won't prosecute over that, it's just a few pence/quid" because they may well do.
In both cases as a taxpayer I object to my money being wasted on that, but it's not up to me, there's nothing I can do to stop it. We may see it as "too costly and time consuming" but those arguments do not apply to the TOCs so it's an irrelevance here.
Applying common sense, I'd have expected in case 1 for the customer to win, and in case 2 for the TOC to win (though I'm glad the TOC lost) however common sense does
not necessarily predict accurately a courts' decision, and the result was the opposite in both cases.