Drinking was by no means less acceptable at the time than smoking pot; the relative ease of getting pot was despite it being frowned upon much more.
Think of it this way: who requires a black market for pot? Every single person who wants pot. Who requires a black market for booze? Not everyone who wants booze... just a narrow band of people spanning 5 or 6 birth years. A group of people who tend to be rather broke.
You can find an adult or two that is willing to buy you a sixpack once in a while fairly easily, but that isn't their job, they couldn't make it their job (since the market is limited and poor), and they probably have more interesting people to hang out with. Pot though? The guy that sells the pot does it for a living. He's going to be far less flaky.
If you, as an adult in an area where medical pot is legal, try to buy pot regularly from somebody who has a medical card, you will likely find that they are less reliable than somebody who does it fulltime. As pot becomes legal to a greater portion of adults, this effect will only increase.
Think of it this way: who requires a black market for pot? Every single person who wants pot. Who requires a black market for booze? Not everyone who wants booze... just a narrow band of people spanning 5 or 6 birth years. A group of people who tend to be rather broke.
You can find an adult or two that is willing to buy you a sixpack once in a while fairly easily, but that isn't their job, they couldn't make it their job (since the market is limited and poor), and they probably have more interesting people to hang out with. Pot though? The guy that sells the pot does it for a living. He's going to be far less flaky.
If you, as an adult in an area where medical pot is legal, try to buy pot regularly from somebody who has a medical card, you will likely find that they are less reliable than somebody who does it fulltime. As pot becomes legal to a greater portion of adults, this effect will only increase.