Example: open source is the communist model, and it works very well. To each according to their need, from each according to their ability. No one owns anything, and you're free to fork or vote with your feet.
Ditto for illegal drug markets. If you're unhappy as a merchant, you have a number of options. No one owns you. You can switch to a different market, or start your own (if you're suicidally ambitious).
The interesting part is that the drug markets end up combining the best of both capitalism and communism in that sense.
But only in that sense. Obviously, unregulated drugs are risky. Yet even without regulations, it's remarkable how rare it is to hear about unhappy customers.