The problem is that so many people who get cracked for DUI end up pleading down to a lesser, non-DUI offense with a penalty that does nothing. In our county, they usually end up having to take a Alcohol/Drug class, pay a fine of, like, $500, and stay out of trouble for 6 months. This is for repeat offenders.
My father is an alcoholic, and has racked up something like 15 DUIs in his life. He still has a license and has never served jail time. What he has is a lawyer who has a good relationship with the prosecutor, and he gets a reckless driving conviction.
And, if we can have some good science that proves out your idea of “sober, buzzed, smashed” I would support some kind of tier-based system. But I don’t think the science holds out - but I could be wrong.