Pizza Delivery and Cops

Is there some sort of unwritten law, or a real law for that matter, that the public knows nothing about, that allows pizza delivery drivers to speed? Because I have to tell you I have noticed many cars with the pizza sign on them buzz past me doing at least 90mph on a 25mph street. Now granted I may not be the fastest driver in the world (my wife will tell you I drive like a grandpa), but come on! I never see those pizza cars pulled over. Do you? I think that the police department is getting some free pizza out of this deal. We make fun of cops for always wanting donuts, but the truth is that pizza is the number one addiction for them. This addiction allows 16 year old kids to cruise around town driving like maniacs in their old Dodge Neon with a pizza sign lit up on top. I mean come on. The light on top of the car even draws attention to the speeding cars and they still don't get pulled over. I challenge somebody to test my theory. Get a hold of one of these pizza signs and drive around town like a crazy person. Speed, hit garbage cans, run red lights, see if you get pulled over. My prediction..............you won't. And no I won't pay for your ticket if you get one. :)