If the phone won’t work when moving unless it’s plugged into your locking gizmo, then a gizmo will need to be installed at every passenger seat of every car and train.
The phone can’t tell if it’s riding on a train or a car; without your magic plug it’ll be dead in either place.
One of the central tenets of tech in business is to never propose a technological solution to a management or social / behavioral problem. It’s guaranteed to fail.
IMO the problem of critically distracted drivers is a social problem. Look for solutions there. Not in tech.
I think it would be for more effective if, when caught, you get both a fine and have your phone shoved up your ass. You get your phone back from the Emergency Room after you pay the bill.
Perhaps we should send them to reeducation camps where they will be forcibly reprogrammed to believe the simple truth that humans cannot multitask and any thought that they can is pure incompetent illusion.
It’d also improve human behavior in a lot of other areas.