Seems to be somewhat luck of the draw. Maybe 3 or 4 years ago, I was on a busy weekend long-distance GWR service into Paddington. A group of four “lads” were brazenly smoking, despite the presence of many children, and laughing and swearing at staff and passengers who asked them to stop.
The Train Manager assured people he was dealing with the matter, and, as we pulled into Platform 1 at Paddington, the BTP welcoming committee was really quite something to behold. Multiple officers were at every single door; they weren’t going to let the miscreants slip through their fingers! Passengers elsewhere on the train must have wondered if a murderer was on the loose.
I’d have liked to watch (and maybe film) what happened next, but I had to get somewhere. I was quite surprised the police cared at all, let alone that much. I presume all those officers were at Paddington because of football fans, and they thought they might as well use them.
I myself reported the same beggar numerous times a couple of years ago, again at Paddington. He would wait at the back of the train for 10+ minutes until it set off, and I would text 61016 with all the details. Easiest plain clothes collar ever, but I rarely even got a reply. See it, say it, sod it.