"If a person needs CPR, they need it now. If a person has a fracture, they can remain still until the ambulance arrives."

Good luck with that. An ambulance can't necessarily arrive, for all kinds of reasons, nor can a victim always remain "still."

BTW, CPR is basically a Hail Mary pass. I understand that roughly 30% of CPR recipients eventually leave thehospital under their own power. Certainly worth doing, but your victim is more likely to die, or is already dead.