Different states have different laws and I assume different questions, especially regarding state laws. I had a lawyer friend that moved from New York back to California and he had to retake the BAR exam. From that perspective the BAR exam would seem to make a lot of sense. On the other hand he was a patent lawyer so I suspect most of the test questions were irrelevant to his actual work. I doubt the different lawyers knowledge base is as radically different compared to different medical specialties though.