These make for interesting thought experiments, but how often will the observable data lead one to a clear cut reliable belief that action A causes X deaths and

These make for interesting thought experiments, but how often will the observable data lead one to a clear cut reliable belief that action A causes X deaths and action B causes Y deaths? And it only gets more challenging if the injures are typically going to be non-life threatening in most cases but could still cause death (there are plenty of cases of people receiving a punch that normally would just bruise but thanks to a stumble or hitting a pavement edge they end up dead?)