Responsibility of owner, registrant and insurance holder for auto liability?

I am wondering who holds the most responsibility for an auto – the owner, the person on the registration or the person with the insurance policy. Assuming that these people are all different.

More specifically, if I have a car on my insurance policy which is owned by someone else and registered to that person am I legally responsible as the policy holder?
Say I am leasing a car, so the title is held by the finance company but the car is registered to me. And my wife is the primary policy holder of the insurance. I am listed as a driver, but the policy is not in my name.

The person who is the principal on the insurance policy is the one held responsible for any claims. It doesn't matter who owns the vehicle, who is driving, or who else is listed as "other drivers" on the policy. That is for claims.

The person who's name appears on the registration (or lease papers) is ultimately responsible for the operation of the vehicle. That is for law suits or illegal operation of the vehicle. (Photo enforcement of laws, illegal parking, damage done to others by the vehicle, etc.)

The person driving the vehicle is responsible for safe and legal operation of the vehicle. That is for vehicle stop tickets. (speeding, reckless driving, etc. where the vehicle is actually stopped by law enforcement.)

An interesting scenario: Vehicle causes a wreck and leaves the scene of an accident. Witness could not see driver, but wrote down license plate number.

The Insured is liable for all damages, the owner (name on registration/lease papers) can be ticketed or arrested unless they give the name of the person using their vehicle at the time, (and signs a legal statement/appears in court to swear to it.) in which case the person actually driving receives the legal penalties.