There's freedom of information, for one thing, and also because a lot of nasty cops will pull people for doing less than 5MPH over, which is garbage because a part of that will be discrepancies between what the radar says and what the driver's speedometer says, and for the rest driving a little over the speedlimit isn't dangerous in most conditions (and if it's not then the speed limit probably isn't safe either).
Gettint pulled over also gives cops leverage to do about anything they want to those.they pull over. They steal, they rape, they plant evidence, they say bird crap and donut glaze is a drug, they'll say a dog that isn't there smelled something, they'll throw your stuff all over the roadside, and if the arrest you for anything, regardless of guilt, you now have a new obstacle and burden tacked on to your life.
I've seen videos where people were pulled over
for these suspicious acts....
- Driving just below the speed limit.
- Driving exactly the speed limti.
- Driving slightly over the speed limit.
As we can observe, the traffic laws are so numerous
& flexible that a cop can pull over anyone just by
following a driver a few minutes, & waiting for an
articulable violation to occur. And then, there is no
threshold below which the cop can't arrest the driver.
Further justification can be invented based upon
highly subjective (non-disprovable) things, eg,
smelling weed, smelling alcohol, air freshener
hanging from the mirror, acting nervous, acting
subdued, glassy eyes, bloodshot eyes, slurred
speech, furtive movements, fitting the description
of a person of interest, laughing, being emotional.