Hence proving my point. You need the right people to enforce, not a passenger host. REOs, Travelsafe officers, BTP or whatever - usually with the relevant clothing (like a stab vest).
Who said a passenger host/guard/OBS/whatever?
All along I've said to copy Merseyrail. It'd be nice if they were more professional as security guards in mainland Europe usually are, but if it's that bad it may be fine that they are a bit thuggy, as that way the local chavvery might actually fear them a bit.
But your point seemed to suggest that only actual Police (armed?) could do the job and that it was so dangerous a squad like this couldn't, and that's, as I said, gross hyperbole. It's bad, but it's not
that bad.
Whilst there are elements of this in the likes of Greater Manchester or Merseyside, in such places it’s still very much the exception, and there’s still a general respect for people in positions of authority.
To be fair I have long held a view that the Northern scally and the Southern chav were a bit different in character, which justified different terms being used for them. The Northern scally might smash up the bus shelter or throw a brick at a train for a laugh with his (almost always male) mates after a can or three of cheap cider in a bus shelter, but if a Policeman or security guard comes they'll just run off as there is, as you say, a genuine fear of/respect for authority where it is present. A typical Merseyside scally would likely engage in casual fare evasion, but wouldn't assault the gateline staff at Liverpool Central, say, they'd just sneak in by getting off at Brunswick or Sandhills where there are no gates. Whereas a London chav would smash up the bus shelter due to genuine malicious feelings and probably assault the gateline staff to get a free trip.
On the other hand I do think the Merseyrail style zero tolerance approach would work. It originates in principle from New York, where, partly due to the addition of handguns to the mix, the kinds of crime and effects of them make south London look like a rural Cotswold village.