In California failing to show proof of financial responsibility, meaning insurance coverage, is a violation of California Vehicle Code Section 16029. Violating this code could result in fines up to $500 plus penalties, impoundment of the vehicle and suspension of the driver's license. If the vehicle is impounded the owner will have to pay for all storage and tow charges as well.
The penalty in California for driving without a license typically includes not only a fine and court fees but the towing and impoundment of the vehicle the unlicensed driver was operating. If you have had a prior conviction for driving as an unlicensed motorist in California, the state may be able to take the vehicle away from you as forfeiture.
In California, it is a misdemeanor to drive without a valid driver's license. It is also mentioned that if the minor does not yet have a license, the minor will be delayed in receiving one. The CA Department of Motor Vehicles should be able to give the minor more information on what licensing penalties may apply for driving before they have obtained a valid license or permit.
Typically the county court of the jurisdiction your son was cited in will assign the fine for his citations. Your 16 year old son that has been cited for these infractions of CA law may try going to the self help CA court site or calling the court listed on the citations to find out more about the penalties he could receive and if this violation of state laws will push back the age which he can apply for a license.
Since your son is a minor and was caught driving without a license, the person who let him drive their vehicle may also get in trouble depending upon state laws. CA Vehicle Code 14607 is titled permitting unlicensed minor to drive and discusses this matter.
Here it states that no person shall cause or knowingly permit his child, ward, or employee under the age of 18 years to drive a motor vehicle upon the highways unless such child, ward, or employee is then licensed under this code. Again the DMV or CA courts will be able to tell you about the penalties the car owner may receive for allowing an unlicensed and uninsured minor drive a car.