CAR Subregulation 166C (2) states that when "operating on the manoeuvring area of, or in the vicinity of, a non‑controlled aerodrome...the pilot must make a broadcast that includes the following information whenever it is reasonably necessary to do so to avoid a collision, or the risk of a collision, with another aircraft..."
Ergo, if there is no risk of a collision there is no mandatory requirement for a call. I'd suggest that covers the majority of VFR operations at unmarked airfields and I would also suggest that the majority of pilots conducting those operations don't bother broadcasting unless it becomes necessary due to other traffic.
Frankly, this whole issue has been blown way out of proportion and has far more to do with political grandstanding than safety.