California voters' 2016 decision tolegalize the recreational use of cannabis was mostly driven by the idea that whether or not to use the drug should be a choice left up to adults — not be dictated by laws written in an era in which "reefer madness" was seen as a societal scourge. But it was also sold in part as a smart way to create a large new revenue stream for local and state governments. While Gavin Newsom, then lieutenant governor and now governor, made this argument as one of the leading voices for the Proposition 64 campaign, he also offered some notes of caution. In a May 2018 intervi...