A quick plug for Haskell Wexler's Bus Rider's Union, which is screening at 9 p.m. on Thursday, Sept. 20, at the Electric Earth CafÃ. Not since Chinatown have we gotten such an intimate look at Los Angeles' public transportation system, this time with Mayor Richard Riordan starring as Noah Cross. And although Wexler is largely preaching to the converted, his documentary faithfully records the continuing struggle of those who, by dint of poverty, are forced to take the bus in this city of cars.