Five years after cannabis legalization, California is awash with signs of an apparently booming industry. Californians can toke on Justin Bieber-branded joints and ash their blunts in Seth Rogen’s $95 ceramics. They can sip on THC-infused seltzers, relax inside a cannabis cafe, and get edibles delivered to their doors. But behind the flashy facade, the legal weed industry remains far from the law-abiding, prosperous sector many had hoped for. In fact, it’s a mess. Voters…