There's merit in that argument, @the_same_mountainbik, but the problem is actually following through with it. Take their car away. They'll buy another one. Take their license away. They'll drive without one and when they get caught, the cop will be nice to them and let them park the car until a licensed driver can move it, and then they'll come back and get it themselves when the cop is gone.
I advocate lengthy jail terms for repeat DUI offenders, and even lengthier ones for repeat offenders who drive without a license. As far as I'm concerned, it's attempted murder.
The only place we really disagree is that I don't advocate punishing someone who didn't drive drunk just because someone who did had borrowed their car. But that wouldn't even be necessary if we did what we needed to do regarding the actual drunk.
They might be temporarily kept from driving drunk if their friend won't lend them a car, at least until they find another car to use, but they'll be unable to drive for a much longer time if they're sitting in a jail cell.
It's infuriating that there are people sitting in jail for minor drug possession charges unrelated to driving, while killers roam the streets too blind-drunk to even realize it when they run someone over.