It seems to me that if the goal is saving lives, then one has to look not only at who harms whom, but also at who is best positioned to prevent that harm. "Pedestrians following the law," who by definition are not jaywalking, are already acting reasonably to protect themselves, so it makes sense to focus on drivers to reduce risks to those pedestrians.

The population of pedestrians who break the law, however, increase the risks to themselves over and above the risks faced by law-abiding pedestrians, by their own actions. (I say this as a pedestrian who commutes to work without driving.) Taking steps to discourage jaywalking encourages that subset of pedestrians to reduce these additional risks and thus saves lives among them. Focusing solely on the wrongdoing of drivers has a certain stern purity, to be sure, but it seems to me to be missing a practical opportunity to achieve benefits on more than one front.