I disagree with that, because the penalties for DUI aren't merely because it is dangerous, but primarily because of the negligent intent related to the act.

And most laws in the US work this way (e.g. they are not strict liability). We often treat people differently based on why a thing happened because doing a bad thing for a bad reason is worse than doing the same thing for any other reason. For example, the penalty for killing a person might range from "absolutely nothing" to "life in prison or death" depending on why it happened.

> Does it state that the list is the exhaustive list? I have a hard time believing that someone could be pulled over, obviously inebriated but get off because they were actually on some new synthetic marijuana that wasn't on that list.

They thought of this -- the list itself includes any "chemical" that is "mind altering", as well as specific drugs.

What it doesn't include is any reason that isn't drugs or alcohol related.