if insurance companies had the sense to refuse to insure anyone

Well there is a sort of "refuse light". Aviva make a great splash of their type of insurance that includes a black box to record speeds and location. The accompanying carrot is lower insurance premiums. And There are still car insurance adverts that expound the virtues of dashcams. Now all we have to do is connect the two and add phones so that any phone usage can be correlated.

And I can prove dashcams improve driving, mine made me far more conscious of road speed limits. Until it packed-up. But get a good one, the resolution - especially in low light levels may not be good enough to prove the other guy was using a phone.