Why set up the system to amortize the public cost of addiction over long periods in the form of hospital visits, lost productivity (both directly due to addiction and indirectly as a result of former criminals' difficulty rejoining the job market), public assistance, court costs, jail costs, and prison costs, rather than focus on rehab and breaking the addiction itself?

If you look at history, drugs were almost never criminalized because they posed a public health crisis - and when they arguably did (as in alcohol prohibition), criminalization created more problems than it solved. Usually the motivations had something to do with xenophobia, moral panic, or politics. Alcohol prohibition was fueled by general animosity towards immigrants (Irish) and a growing Catholic population, with a smattering of both moralism and public health concerns spearheaded by women's rights groups. Marijuana was criminalized largely due to xenophobia toward mexicans and black people. Crack carried harsher penalties than regular cocaine because black people used it. LSD was cracked down on to quell anti-war sentiment in the Vietnam era.

Talking like this frames the narrative and too many of us let these anti-american rhetorical tricks pass without calling it out.

The government has no right to tell me what I can and can't put in my body, whether that's lettuce, Devils lettuce, a cigar, or a soda... doesn't matter.

It's a matter of individual freedom.

Unless you were a child, woman, native, or a slave, right? It also helped to own land.

Come on, we can be against prohibition for practical reasons without resorting to pining for a history which never existed,

First of all, lets just state the fact that the principles of a government can be different from the reality of it. The two aren't mutually exclusive. It's as if by mentioning the worst affected groups you think you magically negate the foundational principles just because the implementation wasn't (and isn't) perfect. It's also not to say the system is theoretically perfect, because it's not, but to use such a logically weak strawman ("pining for a history which never existed") and not even expanding whatsoever is intellectually lazy at best.

"Come on, we can be against prohibition for practical reasons"

The foundational principles of American individualism is the greatest practical reason to be against prohibition. What the hell do you think enabled us to finally get rid of the shackles around those disaffected groups in the first place? It was the hard work that mostly Madison put into researching all the various forms of government, and the greatest political thinkers from around the world, that established a structure that although imperfect would be able to improve over time.

Before we continue this, my main question is whether you are American or not. I find that my approach to this subject needs variation for my friends across the pond. If you are, you need to brush up on your civics.

Other countries have banned slavery, and have enfranchised women, the poor, and people of colour many years before the United States did.

Those countries were not founded on any such principles, nor have they ever claimed that they were. How could they possibly achieve such progressive feats of emancipation?

It's possible to imagine that perhaps, the founding principles weren't of much help in this endeavor. In fact, there's a strong case to be made that none of these achievements had anything to do with the constitution, or the bill of rights, or anything else that the founding fathers wrote about, but did not actually implement - and everything to do with the zeitgeist of the times.