I'm noticing you are mixing up "legal" and "moral" a lot in this thread. They are separate concepts. Just because something is legal doesn't mean it is morally right. Morals are something that someone can chose to live by to help them pick between right and wrong. Laws are literally the absolute bare minimum to participate in society without have your rights to property or freedom revoked. Ideally a common societal agreement of morals and ethics should play in laws, but that doesn't always happen.

> I'm saying that because you haven't killed anyone drunk driving, you're not morally culpable for drunk driving deaths

This is a weird statement... which I guess is true in the narrowest possible meaning. It's true in the way that it is written, but not in a way that matters.

If you drive drunk but haven't killed anyone yet you aren't directly culpable for drunk driving deaths.... but it is still an immoral action. Just because it hasn't caused the worst possible results yet doesn't mean it doesn't significantly raise the risk.