John Allen Paulos has been pushing using toll data for speeding citations for decades, most recently here: http://abcnews.go.com/Technology/WhosCounting/t/story?id=979...
The first is that significant speed differentials are extremely dangerous. Uncalibrated speedometers are very common and very inaccurate. Anything that causes guaranteed enforcement is going to reduce safety because people will start religiously following their speedometer instead of the normal flow of traffic, so now you have people driving all different speeds than one another based on how badly and in which direction their speedometer is miscalibrated. On top of that you have a situation where anyone who has made a stop for coffee or gas is exempt from the timer because of the stop, so you put a number of people driving 15MPH over the limit (because they stopped and aren't subject to the timer) on the same road as people driving 15MPH under the limit (because they haven't stopped and their speedometer is inaccurate) and you're going to see more collisions.
Then there is the pragmatic problem. Speeding tickets are big money because the law is enforced sporadically under unpredictable conditions. To generate revenue, enforcement has to be rare enough that it doesn't induce compliance. And the proposed scheme is entirely deterministic. Everyone who doesn't make a stop will discontinue their speeding between toll booths -- which is ostensibly the intended result, except that it means the scheme will generate no money and will deprive the government of existing ticket revenue that would have been generated on that stretch of road. Meanwhile it reduces the need for police presence, which means you'll have to fight the law enforcement unions to boot. It's not at all surprising that there has been little interest in implementing it.
Why would someone stop, just to get an excuse to speed later, at the same average? The few people drag-racing, maybe. Not the vast majority who want to to arrive at destination ASASP.
You are conjuring up a ridiculous hypothetical and claiming it is the common case.
You do understand that there are service plazas on toll roads. People stop for gas because they need gas, not because they want to speed. But once someone has stopped, or intends to stop before the toll booth, they're no longer subject to the timer and end up creating a dangerous speed differential against the drivers who are.
Is that supposed to be an argument that people won't do it?
>And they could still put some police people on the beat, just to check up on the stoppers.
Or they could just do that to begin with and forget about the toll booths, no?
Also, all the toll roads in South Florida use the same electronic system (EZ-Pass); it's also usable up through Orlando (from personal experience). With such a system, there's no need to even slow down to pay the toll (and there are no more toll booths in Miami; if you have no EZ-Pass system, a photo of your license place is taken, and a bill (not a ticket) is mailed to the license holder).
Edit: There are also three service plazas along the Florida Turnpike in South Florida, one in Dade County (Miami), one in Broward County (just north of Ft. Lauderdale) and one in West Palm Beach (towards the north end of the county), each separated by approximately 30 miles. Depending on where the cop in question lived and worked, he might have never even passed a service plaza (and besides, the gas there is more expensive).
http://www.motorists.org/press/safe-to-raise-freeway-speed-l...
Existing speed limits are pointless but mostly harmless because people just ignore them. Their primary purpose is to serve as a source of ticket revenue and an excuse for police to stop any vehicle they don't otherwise have cause to stop.
the point is that if you intend to stop, or must stop, you are free to speed without fear of automatic ticketing.
I've no empirical evidence, but driving on main roads with average speed cameras feels safer.
Being off by 15MPH is near the edge of the plausible range. What you get when you start with a speedometer that was off by several percent from the factory and then you throw in bald tires, or armchair mechanics who put low profile tires on stock wheels, or replace the differential with one that has a different gear ratio, or damage from a previous collision, etc.