I worked for Wawanese years ago (late 1979/80 time frame). Wawanesa used to require their insureds to sign “exclusions” if there was a less desirable driver in the household. This was used in roommate situations or one example I remember – a household with a 16 year old unlicensed driver, who’d already gotten in an accident. The parents had to sign a form specifically saying that if the kid were driving, it wouldn’t be covered.
Not sure how well these forms would/did hold up in court.