Negligence and punishment. How do we square them?

https://www.theguardian.com/us-news/2023/jan/08/virginia-teacher-shooting-by-six-year-old

The impetus for this is the shooting of a teacher by a 6 year old, made possible by firearm negligence of a parent. But the same thing applies to drunk driving, and almost all forms of negligence.

Let's take drunk driving. We have about a million DUI arrests per year. Those will be punished with some combination of fines, community service, mandatory education, and/or loss of driving privileges.

Roughly one in 10,000 DUI events, however, will randomly cause the loss of somebody else's life. (Estimate assuming that DUI arrests are about 1% of DUI events.) Those drivers will face much more severe penalties. But here's the thing...the 0.01% who killed somebody didn't make worse choices than the 99.99% who didn't. Should they get the heavier punishment and the others the lighter one because of luck?

The drunk driving example isn't the clearest, though, because the person was at the wheel and directly caused the death, which makes severe punishment feel less unfair. What about the case of leaving a loaded, unsecured firearm in the house. Odds are very, very high for each event that nothing bad will happen. But occasionally, one of those events will lead to a death through the action of OTHER people. Is it right to punish that one severely while not punishing the others at all?

Take any form of negligence...improperly secured loads in motor vehicles, or improperly maintained vehicles. If the cargo or loose wheel or bad brakes end up killing someone, is it right to punish that person 100x or 1000x more severely than someone who gets a ticket for an identical infraction?

Maybe it is? Since the overwhelming fraction of DUI events, unsecured firearms, and negligence will never be detected, we can't punish them, so maybe a huge punishment in that negative lottery is effective? Or would we be better off making the punishments for non-lethal infractions a bit steeper, and not charging the unlucky ones with homicide/manslaughter/whatever?