It is very easy for underage people to get hold of alcohol. It is ridiculous to suggest that drugs would be any different. It would make it much easier to buy.
> Beer isn't pure alcohol, McDonald's burgers aren't pure beef, etc.
I still don't understand how you can regulate that. How exactly do you define "not increasingly harmful"? Presumably whatever the definition it risks creating a black market, or being very cheap; both outcomes would be negative.
> Comparing keeping salmonella out of food to keeping drugs clean is apples and oranges - they're entirely different problems.
Why? It would presumably need a similar system of inspection and rules. It doesn't just need to be safe for current drug users, but all the other people that may decide to give it a go. Why would people give up basic consumer rights?