Uber and Lyft drivers chanted and cheered outside the Uber headquarters building in San Francisco on Friday as they delivered a letter demanding negotiations for better working conditions. In an open letter, published to coincide with the protest, drivers called on Uber CEO Dara Khosrowshahi and Lyft co-founders Logan Green and John Zimmer for changes in treatment. Drivers tried to present the letter at the protest, but weren't able to enter Uber's headquarters.