And you didn't notice?

Why in films and television suspects tailed by the cops, or whomever, never notice their being followed?  In every instance the car following is well within view of the suspect.  I mean, you're going to look in your rearview every now and then and you're going to see the same vehicle like 50 feet back right?  Maybe it says something more about the one being followed (that they are an idiot) than the skills of the tailing driver but you think to be less conspicuous you'd want to hang back a ways.  The best is when they follow someone out of the city and then it's just two cars on a lonely dirt road in the middle of nowhere.  Dude!  They're going to notice you behind them for like 20 miles!  Or, maybe I should say, "Dude!  How did you not see the car following you for the last 20 miles and get suspicious?  You're dumping dead hookers in the swamp right while the cops are watching!  How stupid can you be?!"  Rabble-B