Zero tolerance has the same issues as a limit, can you have a couple of glasses lunchtime then drive at 6pm or not. How long do you have to abstain till you can drive, who knows?
I wouldn't give them their licence back ever! It's not a question of how good a driver they are, they might be brilliant sober, but not so good after 10 pints of Strongbow.
I don't see why there isn't a driving life ban on driving with possibly an in house curfew with tags, prison is too costly on the rest of us for their stupidity