In a U.S. context, it is actually really simple. Racism and the age old practice of othering types of people by associating them with a drug (cocaine = rich and white, crack = poor, black and dangerous). That’s it, the full answer is of course a lot more complicated but in the end it is exactly still this dumb and cruel.
politicians across the political divide spent much of the 20th century using marijuana as a means of dividing America. By painting the drug as a scourge from south of the border to a “jazz drug” to the corruptive intoxicant of choice for beatniks and hippies, marijuana as a drug and the laws that sought to control it played on some of America’s worst tendencies around race, ethnicity, civil disobedience, and otherness.
I actually think examining the rise of crack in the US and how it was used as a political wedge and xenophobic tool of fear mongering helps explain why marijuana is illegal in the US the easiest, because the forces and structures are the same for crack being highly illegal as they are for marijuana, just much less thinly veiled and dialed up to 11.
Right, because alcohol is the white man's drug. Plain and simple.
They made alcohol illegal for a while but it turned out to be too onerous for the white people so it was legalized again. Marijuana laws have caused massive damage to minority communities, so they remain in place.
I could see 50+ years from now some Johnny Appleweed from Humboldt County with a family history in black market grow/distribution op running for President.
Marijuana was banned to target minorities, but alcohol prohibition mostly was repealed not because white people like alcohol (white people instituted prohibition in the first place, after all), but because alcohol is stupidly easy to make from a wide variety of substances so most cultures around the world produce some kind of alcohol with their local crops. You can use pretty much anything sugary: fruit (wine), honey (mead), and grains like rice and wheat (sake & beer). It is really hard to ban a substance when half the foods in our diet can be turned into that substance if you let it sit in a jar or bucket in your closet for a few weeks.
Prohibition was repealed primarily because it was a futile effort and with alcohol being banned, very strong distilled spirits were the economical way to discreetly transport and serve alcohol since it is easier to hide a few bottles of liquor from authorities searching your truck or business than to hide large barrels of low ABV drinks like humans had been brewing and drinking for millennia. It is also a lot easier for people to drink themselves sick with distilled drinks, so ultimately it was decided that it was safer to make alcohol legal and regulated instead of having it still plentiful, but getting people sicker and funding criminal empires. It’s a lot easier to ban one plant than to ban every food source with sugar in it, but the marijuana prohibition has clearly led to many of the same problems as alcohol prohibition did.
There are still people who would love to ban alcohol if they feasibly could. Many places in the US still have local alcohol bans, I currently have to travel two counties away to legally purchase liquor and one county away from home to purchase beer or wine. Prohibition only ended on a federal level.
People from Nixon's cabinet have straight up said that they made both illegal and started the "War on Drugs" as justification so that they could lock up opposition leaders in both the black and hippie communities.