Not everyone has people dependent on their income. Is it without harm? No, but it's not the same as putting random innocent people at risk. Even with that, the harm you're talking about is not direct - they lose income, but with drunk driving and smoking people directly die.

That's reasonable. But it's also reasonable to ask what the government's responsibility is in protecting those people.

As a society we've already decided it is the job of the government to at least care for children and other adults who aren't capable through both direct aid and forcing adults to take care of them (child support being the most obvious example).

I'd say it falls into a similar realm -- protecting those who can't protect themselves.