Bad Drivers

Is it just me, or does bad driving come in bunches? What I mean is, how come when somebody commits an act of idiotic driving, seconds or minutes later yet another, and then usually another, person commits other idiotic acts of driving?

And it drives me mad when I pull behind somebody at a light, in the left lane, and just as the light turns green, the person puts on their left turn signal and then I’m stuck behind them. Had I known they were turning right, I would have positioned myself in the left lane and gone around 'em. Oh man, that’s really annoying!