But one thing many don't know is that Prohibition did, in fact, reduce alcohol consumption: As Okrent told me, tax stamps from before and after Prohibition's passage suggest there was, indeed, a decline in drinking — one that was sustained for several years.
What? If there is a large illegal markets for alcohol sales, how can tax stamps be considered an indication of alcohol sales?
But after these huge, untaxed channels of getting alcohol to Americans were established, why would we expect all of them to go legal after repeal? Would that in fact make them more vulnerable to criminal charges, tax evasion at the least, from their past actions?
If you've already built the infrastructure and practices to smuggle an illegal good, it is unlikely that you immediately start paying taxes once it becomes legal.
The illegal sale of something has risks and costs (obviously) so the criminals will only engage in it if the price of the good being sold is high enough. When prohibition started the price of alcohol went up to cover the risk of selling it illegally. Once prohibition ended the price dropped and it was no longer worth the risk to selling it illegally.
However, you are correct that they had already built up the infrastructure and practices for smuggling, so they simply moved to other more profitable goods like guns, harder drugs, and people.
Assuming the black-market networks created as a response to prohibition shut down completely, of course. They may have continued operating as a means of tax avoidance, leading to less taxed consumption post-prohibition.
What? If there is a large illegal markets for alcohol sales, how can tax stamps be considered an indication of alcohol sales?