<nitpick> The code for Bristol Temple Meads is BRI, not BTM.</nitpick> Although BTM is not a valid station, so less confusion than when people write BNS (Barnes) meaning Birmingham New Street (BHM)!
Or worse, "ELY to LLS" (Ely to Llanishen) when there are direct trains to two possible places that they could mean; London Liverpool Street or Liverpool Lime Street!
The 3-letter codes are in so many places now, there really is no excuse!
- Throughout the National Rail website including the journey planner, Stations made Easy, etc.
- Most, if not all, ticket booking websites including Thetrainline, WebTIS, etc.
- Avantix Traveller
- Live Departure boards
- Many 3rd party apps
I can think of numerous occasions when I've seen someone with a ticket irregularity or no ticket at all and said nothing but alerted barrier staff at the station they were alighting at, had a reception committee waiting, or knew I would see them again and could catch them next time I had back-up.
Yeah, the passenger may not know what is going on 'behind the scenes'.
Three people from Bishops Stortford who thought they had got away with 'effing it' from London to Leeds a few days ago thought they had got away with it, until the train was met at BTP at Doncaster. They didn't see that coming. Oh, and that was the last train to Leeds and the last train to
anywhere departed shortly after. Even better, one of them realised mid-journey that he had advertised his little excursion on Facebook and that people he worked with would probably tell his boss the real reason why he hadn't turned up to work. That'll be a trip they won't forget for sure!

But anyone who got off the train before Donny would have thought they were going to get away with it.