Right, like drugs. Libertarians refuse to see that allowing everyone to use dangerous narcotic drugs, as an example, leads inevitably to an increase in violent crime and theft and driving under the influence of drugs (which leads to innocent death). By the time the offender has been punished, the crime has been done. They're like the Catholic bishops, who wish to punish homosexual teenage boy molesters after they've committed the crime. By then, the teenage boy has already been horribly harmed.
As for your argument that driving under the influence of drugs is any more dangerous than driving drunk, that's totally inane. An intoxicated driver is just as dangerous regardless of whether he/she is drunk or stoned. Singling out drug users is not going to save anyone. We have judges who won't hesitate to lock up a pothead who drives stoned but won't lock up drunk drivers because the judges themselves are drinkers. One drunk driver who was arrested in VA had 8 DUIs in NC for which he served virtually no jail time. It finally took one of our judges giving him a 5 year felony sentence for his 9th DUI to get him off the streets. Until you get every judge like that off the bench, don't talk to me about the dangers of drug users behind the wheels. Drinkers are far more dangerous because drinking judges often won't give them harsh sentences.