The problem I have with Laser speed guns is thier ability to read a good speed:
They take a third of a second to read.
In this time, the beam can go from the top of your windshield to the front plate generating an error of 5MPH
The beams DO NOT stay at a pencil point, they deviate greatly.
A test of one gun showed that it emmitted THREE beams, all were about 6' wide at 1/4 mile (where they like to measure) and none were on center.
Optics are fragile.
Cops don't treat them like they would need to (as soon as they go for a drive they beat them to hell) to keep them dead on accurate.
To "pick out" a single car, you need to have a very good, and steady aim.
Can you hit a car with a handgun reliably at 1/4 mile? That's what you'd need to do.
IMO, radar is more reliable since it measures effectively the fastest moving reflection. Who's to say the laser beam didn't start on another car and move to yours in that 1/3rd of a second? Just too much error if you ask me.