It seems like you're effectively saying MADD didn't work. Drunk driving never became less than it was in the late 1970s

https://en.wikipedia.org/wiki/Mothers_Against_Drunk_Driving

The claim they lowered drunk driving deaths by 1/2. I have no easy way to verify that but if true it certainly suggests people's behavior can be changed

I don't know about your area, but where I live the police set up checkpoints along common routes home from popular bars/restaurants to catch drunk drivers. Drunk drivers get caught extremely often and many of them lose their licence for long periods of time.

This does not discourage drunk driving as much as you would think. It does remove a lot of the drunk drivers from the road by force, however.

MADD only worked in the sense that it made some mothers feel somewhat absolved of whatever guilt they felt for losing a child. Their statistical claims are quite ridiculous, though.

Edit: Claiming credit moreso than flawed statistics, although both are highly questionable.

Enforcement works in societies which actually enforce their laws. Try finding weed in Singapore for example.

Do NOT try to get weed there.

You probably could, however, find hordes of repressed maniacs and neurotics discouraged enough by it to hesitate a bit. At least if you could keep them out of motor vehicles ;)