I'm assuming that's the same Dr. Carl Hart from this interview?

Driving was my go-to analogy too (I've got a longer post where I go into it) Surely there's the concept of legal drugs though too? You're allowed to have wine, but not drive at 120 miles per hour past school gates.

My feeling is that there's a difference between "safe" and "worth the risk". And as far as lawmakers are concerned, for most drugs there's not case where it's worth the risks.