why?冇可能係零失業率?

每個地方都有一個叫做natural rate of unemployment.
因為有好多原因: imperfect information
the buffer of changing another job
others ( sickness of ppl lead to a temperarly quit the job)
其實仲冇好多其他原因ga, 好似有冇聽過有人專登quit 左個job, 跟著就去旅行or "充電". 佢地唔係唔需要工作wor, 只不過唔做住先姐, 所以都係unemployment ga.
向econ 的角度, full employment 就mean within 個natural rate of umempoyment.
向香港, d 人會做工"駁" d, 所以個natural rate 會比較細d, 向外國, 特別europe o個dcountries 會大好多tim. 都係depends on 個culture.
另外, imperfect information, 如果你係預科, 咁應該學左個transaction cost, 咁society 會set up d institutes 去reduce 個transaction cost ( information cost 係其中一種), labour department 係institutes 的其中一種.