By Kathleen Ronayne, The Associated Press Uber, Lyft and DoorDash threatened Thursday to spend at least $90 million on a California ballot measure if they can’t reach a deal with unions and lawmakers on legislation that would change the rights of their drivers and other so-called gig workers. “We remain focused on reaching a deal, and are confident about bringing this issue to the voters if necessary,” Adrian Durbin, senior director of communications at Lyft, said in a statement. The companies’ collaboration comes as California lawmakers debate a bill that would make it harder to classify workers as independent contractors instead of employees. As employees, workers are entitled to more wage protections and benefits. But the companies say labeling them as such would upend their business model built around driver flexibility. The California Labor Federation, which sponsored the bill, quickly vowed to fight a ballot measure. “We will meet the gig companies’ absurd political spendin...