How the Architect of California’s Billionaire Tax Became Tech’s Villain

Around the time he filed the billionaire tax proposal that has shaken up the tech world and ignited a debate about wealth taxes nationwide, Dave Regan, president of the California-based union behind the effort, convened a group of fellow labor leaders to solicit their thoughts. In a videoconference, he told the group he had a 30-day period to finalize the measure, which would assess a one-time, 5% tax on the assets of every billionaire in the state to backfill $100 billion in...