Why are some of these legal questions so ridiculously unrelated to the act of operating a motor vehicle?

You're right - your written knowledge test is not a bar exam.
Please keep in mind that the real test has questions from different sections of the official manual, including the DUI limits, fines and punishments. You have to study the Handbook first from cover to cover and then proceed with the practice tests to maximize your chances to nail your real exam on your first attempt.