3 inches is not very much snow. A driver should also be far enough behind the car in front of them that the front car's rear bumper can fall off and the rear driver won't hit it. 3 seconds is the rule of thumb for the distance between you and the car in front of you, and if the roads are even a little tricky, 4 seconds is more appropriate. If they are going to enforce a couple of inches of snow on the roof of the car, they should use AI to track tailgating. If every car on the Merritt one morning gets a ticket, then that is the way it goes.
I looked up the NH law, and that involved a situation with a truck, which is a bit different.