I hadn't heard about an incident in Toby. It's a little different if they were inside the park, as it's a National Park and has it's own legally enforcable rules in the park, where a dive flag is required and boats are required to respect it. So an issue settled under those terms, in Canada, may not apply anywhere else in Canada.
Many of the incidents that have been mentioned in passing, such as at least one death of a BOW student near Barrie, are cases where divers are diving in or near marked navigation channels and beside docks. And I always thought the purpose of a dock, was to tie up a boat, therefore any diver diving within 100 feet of a dock, should expect boats in the vicinity.
It's kinda like diving a motorcycle. Even if you do have the right of way, in the case of a collision, you might be dead right.
The red and white dive flag has no legal standing in Canadian Federal Law as far as right of way and distances. Where it is mentioned by Transport Canada, it's only mentioned for boaters and then as a minimum 1 meter rigid flag. Hard to make the jump from that to a 12 inch flag on a small float, being towed by a diver. And speaking as a boater, the average dive flag/float is almost impossible to see until your right on top of it. Our local club uses 3 foot inflateable bright orange tetrahedrons as race markers and they're hard enough to see, when you're actively searching for them, at anything much over 1/4 mile.
I agree that an educational campaign would be time and $$ well spent.