It stops by far most people from driving. The ones who are undeterred and keep on driving without a license are then fair game for the criminal justice system.

It stops by far most people from driving. The ones who are undeterred and keep on driving without a license are then fair game for the criminal justice system. Even if this minority gets away with continue driving without a license and wont get punished, you still save many lives by taking the vast majority of drunk drivers off the road. That alone is worth it.