Pricing for auto insurance is all fully public information, that states' approve. There is no "discretion". You can look it up yourself. Search for "SERFF" and your state.
Also, auto insurance has the lowest profit margins of any type of insurance.
Unfortunately, in some states, even after reading and cross-referencing dozens of obtuse rules and tables from a given company's rules and rates filing, you may eventually find that the final premium relies on the output of some manner of GLM/tree model that you'll never have access to.
True, you might need to review those rate/rule filings across several states to tease out the more obscure aspects...or any large actuarial firm can do it for you.
Also, auto insurance has the lowest profit margins of any type of insurance.