Some of them are poor slobs. Some of them are organized crime.
Are they just going to try to sell it at a lower price since the police cannot tell where you got it from and might not even care anymore? Tax savings alone radically reduces the price.
Alcohol flows plentifully and relatively cheaply here though although I hear there are speak easies.
So I guess the moral is, if you tax it so much people are paying exorbitant amounts for it, you may end up creating a bootlegger's market, especially if you don't have to cross any national borders with the product.
http://www.nytimes.com/2011/04/05/nyregion/05loosie.html?pag...
I dunno...but, we didn't, as a nation, mourn the end of bootlegging as a career option when alcohol prohibition ended. So, I'm not going to mourn the end of the small-time drug dealer (or the large scale cartel dealers, either).
If you have the right (or wrong, depends on how you view it) friends, then booze will be almost always available. Your friend doesn't necessarily need to be old enough to buy the booze, since if she/he has the contacts to yet older friends then you can understand how the buying circulates trough different levels. This way you don't necessarily need more than one middleman to buy vodka at age of 17.
Tobacco gets usually passed on the same way as booze, but at least in case of snus there are usually known groups which adopt the use. For example, hockey players are known to use snus, so there's high chance that you can buy some from them. And you don't need to know more than one hockey player, as the players know which one of their teammates has the stuff and when.
In cases where some known groups have the substances and the interest to sell them, you could consider it as somewhat centralized market. The people who run the market don't likely think it as one, but that's up to the viewer. After all, the way the liquer and tobacco gets spread may seem like there's no market at all.
This is one of the braking factors on tobacco taxes. It applies to any market -- if the taxes are too high, people will cheat the taxes.
Edit: I see the first link by @munin refers to a Virginia-to-NY cig smuggling scheme.
Another anecdote: at my high school there were several people involved in a ring of cigarette carton theft, who would then sell cartons at the school for inflated prices.