I'm not saying that they shouldn't have manual revenue protection

I'm just saying that "being seen to have it" isn't a reason for
having it.
The people who cheat know that they are cheating - they don't need the
presence of inspectors to remind them


I am not sure your argument takes account of the behavioural effects of
things like visible revenue protection officers on normative behaviour.
I don't know of detailed research on the effects on travel but there is
quite a long history of research on the effect on taxpayers (and
non-payers) which suggests levels of vountary compliance increase with
an increased perception that non-compliance is low or that there
non-compliance carries significant risks of penalties/conviction. In
other words, the target population is not just those who are cheating,
it's also those who might be tempted to cheat.
--
Robin
reply to address is (meant to be) valid