As others have said, regular assessment would be costly and wouldn't improve the situation one jot.
Consider the classroom full of rowdy students who suddenly rush to their desks as soon as they hear the teacher coming and sit there like butter wouldn't melt as he walks into the room.
What we need is driver re-education - teaching people that by sitting back, relaxing, and being attentive to other road users the driver will still get to their destination in time. I think it's important to teach people to see the vehicle and not the driver - as soon as we see another vehicle as a driver then we imbue it will a personality and a brain and something to be interacted with. If we just see it as a large lump of metal travelling at high speed, then we see it as a hazard to be noted and tracked in case it does something dangerous. For example, if someone accidentally dropped a hammer on you, you wouldn't get pissed off with the hammer, would you?
The other thing that aggressive drivers need to be taught is that 99% of "cut-ups" are not deliberate - they occur just because the other driver is not paying attention. A picture-perfect example of this happened just yesterday as I was riding my motorbike through rush-hour traffic into Chichester - I was overtaking a stationary column of traffic when a white van just pulled out directly into my path. I sounded a horn and applied the brakes pretty sharply! When I pulled alongside, I gave the driver a long, hard stare and he looked shocked and waved at me apologetically and I could see him saying "I'm sorry". What good would it have done for me to loose my rag in that situation? How would it have helped anyone? Not at all! I just shook my head and carried on. It wasn't a personal attack against me, the idiot just didn't look! I was prepared for that and took the necessary action without getting angry and confontational.