The fact that only a minority of journeys are impacted doesn't negate the huge scale of the problem.
You only need to mistreat someone once for that person to never want to return; and for them to tell friends and family of their experience.
The rail industry has a terrible image problem when it comes to poor treatment of customers; I am not sure if anyone has conducted a study to gather results that are very specific towards this principle, but in a related piece of work from 2018 we have some hints:
Views of rail passengers on rail fares and pricing from research conducted in 2018 and 2019.
www.gov.uk
There has been a huge move towards harsher treatment of customers since 2018.
Here is a comment from a news article which gives an idea of what some people think:
Those passengers who purchase the wrong ticket for use with their Railcard on a train can find themselves hit with a fine - or worse, a criminal conviction on their record.
www.dailymail.co.uk
There are plenty more in a similar vein, which demonstrates how even just
one shocking case can have a disproportionate affect.
Complex rules leave many customers feeling caught out and annoyed they aren't made clearer by rail companies.
www.bbc.co.uk
As you can see, such poor treatment angers people to the extent that they feel that it is indicative of a wider problem; the actions of some rail staff/customers can actually have a negative effect on how people percieve the 'country' as a whole.
The problem with a lot of the research is that it focusses on the fares themselves being unfair, but that's a different debate, which has been done to death elsewhere and has no solution everyone can agree on; but a common theme is that if you ask people why they are concerned about fares being confusing, e.g. "off peak" etc, it is because of the perception of harsh concequences if they get it wrong.
Some people will choose to overpay if in doubt as they cannot face the risk of harsh treatment later; this is even the case where only the difference would be payable.
I've been on trains where people have been exasperated at the way they, or others around them, have been treated for having the wrong ticket.
Here are some more views from Facebook recently:
"Why would anyone get the train if this is how they will treat you?"
www.facebook.com
.
.
I could go on, but you are not going to change your mind, no matter how much evidence is presented.
But it doesn't matter; I don't need to convince you that the rail industry has a huge perception problem as it really won't make any difference either way if you think that there isn't a problem.