The other month there was a group of staff at Guildford, at the bottom of the stairs to platform 1 and 2. Whilst I imagine they were there for passengers arriving, they were checking passenger going down the stairs too.
However they were not checking the stairs that lead to platform 2 and nor were they checking platform 3, which also has metro arrivals too. I've never seen that platform checked yet
Guildford has barriers but not all the surbuban stations do.
Unbarriered stations do get staff from time to time but once I was at Hinchley Wood and the staff were only covering the stairs to the footbridge and not the footpath exit to the playing field.
I don't know if their interest that day was more for people arriving to catch a train than those leaving a train.
Many years ago Guildford had a police presence to check for knives etc. Used a metal detector and closed the ba k of Guildford Station.
The next day some teenager dropped a bottle that smashed, on the way out of the back entrance. They said to the person with them, something along the lines of, I can do this here becuae the police don't come to this side.