From life experience It seams to me that a large % of drink drivers are alcoholics/heavy drinkers who regularly drive over the limit.
I think a large proportion of these people with drink problems are repeat offenders who can't help themselves and continue to risk other peoples life's no matter what, even if they are banned,fined and or locked up .
What doesn't help is the ridiculously low fines they get when caught in this country.
A £3000 fine plus a 3 year ban would be more like it even if they didn't cause injury or death.