Because we were making general statements about the nature of humans and the nature of governments.
There are glaringly obvious counter-examples that contradict your assertions regarding murder vs. drug use.
I was making reference only to United States -- a first world developed country.
My example of Buchenwald refered to a smug, first world country. If Buchenwald can happen in the land of Goethe and Bach, you shouldn't kid yourself about what might happen in the land of Jefferson and Twain.
Following your logic if there was an easy way to hide dead bodies leaving no trace back to the murderer then there would be as many murderers as people that smoke pot.
As I said, its purely a matter of consequences.
You can law with consequences or law without consequences (8 years is the average America punishment for murder these days, far lower than say the Icelandic Vikings Anarcho-Capitalist price).
You can law with consequences or law without consequences
This is what I proposes: When a person thinks they've been harmed by another person they can file criminal charges and or file a civil lawsuit claim against the suspect. Thus just laws prohibit murder, rape, assault, robbery, blackmail and fraud. Prohibiting any act wherein a person initiates force, threat of force or fraud against a person or their property.
There is no need for laws that prohibit acts between consenting adults because if a third person is harmed by the actions of either or both the consenting adults they can file a civil lawsuit to gain restitution. If one or both consenting adults assault a third person or commits fraud against a third person the third person/victim can file criminal charges. It's the same for a lone individual that acts without engaging any other person or another person's property.
In criminal and civil court trials impartial juries can decide if the charges are valid or if an acquittal is called for.
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The lack of impartial juries has been the lynch pin to deteriorate moral compasses while creating the illusion of separation of powers that it subverts.