Let me try to clarify: if you have rules prohibiting the creation and sale of substances solely for personal consumption by competent, consenting adults, then you have the primary tool needed to conduct a War on Drugs. I think that it is a mistaken notion to imagine creating this power, and saying "don't worry, we'll only ban dangerous things, and not harmless things, because we'll know better." I think that is definitely not the case. Yes, many people want a different mix of things banned and permitted. But people should not fool themselves into thinking that is what they will get, because a power like that is pretty much always used for more things than its creators intend. We cannot simultaneously prohibit things, and not enforce that prohibition through, ultimately, threats of imprisonment. If the maximum penalty for a drug charge is a ticket, then the prohibition on drugs will simply not be effective.

The War on Drugs has involved arresting and imprisoning a lot of people, because a lot of people really want drugs. Once the soft enforcement mechanisms (reprimands, misdemeanors, fines of legitimate businesses) fail, then if you really want to suppress the act, you have to ramp up the level of force. The reason that fewer people are imprisoned under FDA rulings is, I would say, because the FDA is more lenient, and because the things it bans are far more niche and less desired. You can have effective, or you can have gentle, but you cannot have both.

I recognized that you think it's a slippery slope, I'm not sure what you think I'm not getting.

I do believe that you can tell store fronts not to market literal gasoline as a restorative tonic without automatically escalating to violent raids. As far as I can tell, a rule against marketing gasoline as a restorative falls afoul of the standard you declare in your first sentence. People aren't very comfortable shrugging and not doing anything about perceived problems (illicit distribution of the restorative gasoline), but we'd be better off if we did that more often.

(I do understand that the example is ridiculous because there is no demand for a restorative gasoline tonic amongst competent adults, it's just that there is ample evidence that people want some assurances about safety. A less ridiculous example would be requiring people buying cocaine to go through some sort of educational material that made the risk of forming a habit clear, and regulating the manufacture of the cocaine that is eventually sold so that it is not adulterated)

Yes, of course, rules against incorrectly marked or marketed or adulterated products are different from the war on drugs. What I'm saying is that drug-war-type activities are based on rules prohibiting the sale of particular goods even with zero promises as to their safety or efficacy. (And the FDA does enforce a number of such rules, though certainly not that many compared to other bodies.)

If someone was convinced that gasoline would cure their hair loss, they couldn't get it through a pharmacy, but they could still get it from someone making no such promises. If someone was convinced that cocaine would cure their hair loss, they can't get it any way, any how - even just as something labelled "dangerous goods, do not consume". That's the prohibitive authority that leads to raids and cartel warfare. And that's the power that many people still support the FDA/DEA/government having, and which I am pointing out is the root of the problems with the drug war.