San Francisco cabdrivers have decided that it’s time to form a union. The local industry has been reeling for years as venture capital-backed ride services like Uber and Lyft have proliferated and taxi companies’ calls to The City to level the playing field have done little to help. On Wednesday, cab drivers voted to initiate the San Francisco Taxi Workers Alliance, an affiliate of the American Federation of Labor and Congress of Industrial Organizations (AFL-CIO)…