Amazingly, people often fail to respond to negative incentives, because they think they will be lucky enough to avoid them. See: - heart attacks - lung disease - saving for retirement - vehicle emissions - etc.

And, even if you can’t afford the punishment for killing another human being, you might still be able to afford to take the risk to do so. It’s a sort of lessor version of a free-rider problem.

Even there, this is assuming that people that take on this level of personal liability are even aware that they are taking that risk.

negative incentives works otherwise we wouldn't have it. Does it work perfectly ? no. The goal is to reduce. To eliminate completely maybe impossible.

Preventative medicine is the most effective treatment.