A good driver will first notice they are in an unnecessary clump, and a bad driver probably won't.
A good driver will try to minimize the the time they spend relatively motionless to other cars (other than behind them at a safe follow distance). A bad driver either doesn't realize as in the previous point, doesn't care, or actually prefers it as some kind of crutch. Sometimes the leader of the clump ends up that way because they will speed up whenever those behind them try to pass. Sometimes the rear of the pack is a driving zombie who will close any distance between them and the car in front, but will never choose to pass. And so on...
The tall vehicle behind the Tesla will hide the fact that the slow Tesla on the left lane is slow for no reason, people behind the tall vehicle will think there is traffic. And we will all go 55 on the left lane, thinking there is traffic. Until some incline allows people to see that there is no real traffic and then the Tesla gets overtaken and clump is broken.
