There are 50 states plus DC. (expand this by other countries, territories, provinces, etc.) Each state has its own laws and each company has its own loss experience. Each state is going to have its own product manager (each PM can have more than one state) that is responsible for profit in the state. State Farm could raise rates in one state because loss experience dictates that, while dropping them in another because they are looking for more market share. Auto insurance is something you can't compare across people - at all. You can compare rates for YOU across companies, but your rate has nothing to do with anyone else's rate.
You can’t compare absolute numbers but you can compare relative numbers. As well as quality of service etc.
Progressive has been consistently low for lots of folks.
I also think the insurance companies share a database for stats on vehicles.