Wheat is not a good comparison because it's mostly not consumer facing. Consumers care for more things in their purchases than just the raw good. Your alcohol example IS a good example. Consumers aren't just buying a beverage that intoxicates them that doesn't taste terrible. They pay a premium for brand, image, and to a large extent placebo quality. The cost of manufacturing for most alcoholic beverages has little to do with the final price.

Hell, even look at legal, non-recreational drugs. There can be an identical generic version. There can be an accredited medical professional standing right there saying "they're the same thing" and people will still opt for name brand.

I'm certain that if drugs were legalised, all that extra cost from being illegal would go straight in to marketing budgets and people will be buying the lsd equivalent of $300 bottles of wine or vodka that comes in creative packaging.