There was a deep divide between ATC and FS in the '60's and early '70's. The classification of ATC was third division in the PS and FS was forth division. As a result there were differences in employment conditions etc etc. That difference in fact was the line that FS could not cross and have access to radar - it was just not in the PS thinking back then. Safety was not a consideration it seemed.
There was even one senior DCA manager that had responsibility for FS and he liked to ensure that the new FSU's that were built around the country in the '60's had no view of the aerodrome, however he was not always successful. Derby had a good view from the 1st floor. Meeka faced away from the movement area as did Mildura. Hedland had a view till they built the tower in front. Most of the old buildings a very limited view without stepping out the door. In fact at Mildura, they had a speaker mounted in the lunch room which had a door that when opened had a good view of the aerodrome. One of the techs rigged up a mike on a long lead and on a good day the FSO could sit outside and do the job!! Dubbo was one of the better ones with that little tower and I recall Devonport was similar.
In Melb in the '70's, the only way a VFR could get to talk to ATC when OCTA was for FS to declare an uncertainty phase on the aircraft due lost or position doubtful etc and transfer to Approach etc for ident. That in fact was not uncommon. Some pilots even refused to transfer as they knew a 225 was around the corner!!