Early on in Jia Zhangke’s “Caught by the Tides,” a woman in her twenties, Qiaoqiao (Zhao Tao), tries to escape her boyfriend, Guo Bin (Li Zhubin). Lord, how she tries. It’s 2001, and the two are alone on a bus, parked somewhere in Datong, a coal-mining city in northern China. Whenever Qiaoqiao tries to get up and bolt for the exit, Bin hurls her back down into her seat—up and down, up and down, eleven times in a row, until Qiaoqiao, in tears, finally breaks free on the twelfth attempt. You may wonder how the director and actors choreographed this wordless clash of wills: How many throwdowns would suffice? Did Jia, a master of on-the-fly realism, instruct Zhao and Li to improvise—to run through the action again and again, in…