英语语法,关于that 和 one

题目

英语语法,关于that 和 one
原题是这样的：The television repairman who wears a uniform tends to inspire more trust than ( ) who appears in civilian clothes.
按我的理解的话,括号中理应填the television repairman.这应该是没错的吧,因为对应题干用“THE+可数名词单数”表示泛指.那么,这样一来就可以用the one 但答案是one.之前一位高手说“凡是表泛指的代词单数就用ONE.如果用THE ONE或THAT就是特指了（指具体的一个人）”.这种分辨代词ONE和the one/that的方法正确么?
我一开始觉得有道理,不过后来又看到了这句话(不是我自己瞎编的,是来自一本书）：
You've probably heard of fair-weather friends.They're the ones who are happy to be around you when things are going well,but are nowhere to be found when you really need them.这里很明显也是泛指这一类人,但为什么没用ones,反而加了The?这不是特指了么?

答案

上一句话是说任一穿便装的人.下一句话还是有所圈定的.