Actually, most schools do not prepare you for the actual workforce. I went to an engineering school, which tends to teach more real world subject matter and gives projects that are relevant to current technology, at least sometimes. The school itself though, didn't really "prepare" you for the job, all it is there for, is to open doors for actual employment, where you will learn the job. Engineering schools often require students to gain technical work experience, my old school being one of them, because they know perfectly well that is where you will really gain the experience you need to hit the ground running when you graduate.
I imagine it is much worse for liberal arts majors, since there isn't really a good internship/co-op system for them AND since their education is so broad, it is unlikely they were able to take more than a small handful of classes that are even relevant to what they end up doing, much less useful.
Law school is the same, it is there to facilitate you getting a good job.