As I'm retired (which I told them), I don't have the need to drive much, but I sometimes drive my Wife's car, which she uses it for work, and I am definitely not the main driver. I do more miles on my pedal bike than I ever do it the car (and certainly more hours). It grates that they think everyone uses a car..... What next, they join forces with BBC and use detector vans, because everyone MUST use a car and a TV?
Well I suspect that the vast majority of people getting car insurance quotes do in fact use a car.
They don't know you're not the main driver of your wife's car. Your not driving another car much is unusual, so they're just checking. A lot of people bend the truth (lie) to get a cheaper quote.