Here's the thing though - cars, knives, gun etc do not interfere with judgement, and so you can act rationally in their use. Drugs target your perception of reality and so your judgement becomes impaired and you are very much not in your right mind when under the influence.
It all comes down to personal responsbility. There are lots of things in our society that are potentially lethal like cars, knives, even guns, but we allow people to use them responsibly, and if they abuse that right, we take it away. Drugs should be the same.
As to alcohol being a throwback, I meant that in terms of it being more addictive, more socially damaging and worse for you than many banned substances.