Chilli Monster said :-
is down to the individual controllers who provide the service, not the infrastructure available
This hits the nail on the head. It is the hardest thing in the world after all the training and constant spamming about looking after pilots with DoC not to call traffic to a FIS.
We often have discussions at work about this very subject. It is a very hard thing to predict a merge or hairsbredth of daylight. One person's view of near is different to anothers, even with standardisation.
Another thing. I would like squawks to remain on FIS aircraft, because they are there for the use of other angencies as well as a source of ident.