I'm not so sure it'll be fun for everyone... that is only a couple of steps away from a Black Mirror episode (specifically S03E01, Nosedive). The risk of 'poor driver' ostracism/stigma is significant.
The road is a public space where privacy is not expected, and your behavior directly affects the safety of others. I'm not sure that we ought to protect "safe space to be a bad driver" the way other personality differences ought to be protected.
You assume that bad driving is a fixed trait. In addition, driver 'ratings' are given by other humans in the proposed system; humans are biased and sometimes even spiteful on the roads. A rating system sounds great in theory but wouldn't actually work.
