Oh please, if lawyers knew how to do these things then God wouldn’t have had to invent paralegals!
:::d&r:::
No silly, God made paralegals in response to law schools like Western State! 
Seriously though, law schools do try to teach persuasion, as much as it CAN be taught, and that is absolutely vital to passing the CA Bar.
The CA Bar exam is 1/3 standardized and 2/3 subjective, in terms of grading. Those fine folks grading your essays are active CA lawyers getting paid approximately $2.50 per essay to read, evaluate and grade (I won’t even say what I think about this). Also, you have to average 85 on every essay in order to pass. Therefore, if your writing is subpar, you have trouble getting your point across, or have other problems writing coherantly, the grader may not even read your whole essay before he/she gives you a 65.
Hell, law schools also prepare you for a law career by exposing you to three straight years of unfairness, capriciousness, bitter fighting, overwhelming workload and unbelievable stress. If you don’t like it, law may not be your field after all.
FWIW: A list of the six states allowing folks to take the Bar after an apprenticeship can be found here (see John Bear’s post):
http://www.degreeinfo.com/forums/showthread.php?s=&threadid=4804
Cheers,
This question isn’t too much different than asking “Why go to school if you can get a library card for free?” If you’re extremely motivated and talented, you can learn it all on your own, but most of us need the structure of a university setting to gain a high level of knowledge and expertise.
When I went to CA law school in the mid 80s, rumor had it that you could still “read” to become a lawyer. This link: http://www.calbar.org/admissions/prelegallinks.htm suggests that it is still possible in California