The standard Auto policy will cover your “Family Member” (although there are some that will not), even if they are not a known operator. However, being that all operators are supposed to be on the “declarations” page, if someone “forgot” to add an operator, that operator may be denied (especially if there is a large claim) if they were operating the vehicle at the time. Furthermore, if the company asks for the names of all operators and there is an omission, that would be fraud and the company would probably deny your claim.
As an additional point, if your son drives someone elses car, he may not be covered either unless the named insured (parent or spouse) allows them to drive on an occasional basis. If your son’s friend allows him to drive an auto under his parents’ policy, their auto insurer is within their rights to deny coverage (reasonable belief exclusion).
My suggestion to you is to speak to your agent about placing your child on as a “non principal operator”, which can significantly lower his premium.
(Let me note that none of this should be construed as legal advice).
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