Prior to the 1991 AMATS changes all VFR above 5000' in G gave mandatory full position reports as IFR and VFR flew at the same levels.
Don't think there was 'G' prior to AMATS? Just Uncontrolled, which meant UNcontrolled, not sort of uncontrolled, or a bit uncontrolled, or am I uncontrolled.
Both IFR and VFR could not even communicate to a radar controller even when in radar airspace.
But in Controlled Airspace, they both spoke directly to an ATC, irrespective of radar availability, and OCTA, 99.9% of the time, they didn't need to speak to a controller, radar or otherwise.
That's why I made the changes.
And 25 years later, we are still dealing with them.