couldn't figure out how something was going to detect someone else getting lased
Ah, I see what you're getting at now. For exactly the reasons you listed, they do not work well.
Our research showed that most of the energy was going to go pretty much straight back to the cop
This isn't necessarily accurate. The beam produced is slightly cone-shaped (typically 1-2 degrees, producing a 'spot' about 3' in diameter at its usual useable range), and a typical car isn't flat, so there will be some scatter. Generally speaking, in practice, when in use the guns are aimed at the car's license plate, as it is typically the flattest metallic surface.
It is true that it is difficult to separate lidar from sunlight, but, going back to my low-tech analogy: your television, even if the sun is shining on it, can usually still receive the pulses from a remote, although typically at reduced range. Its all a matter of the electronics being sensative enough to work at a poor signal-to-noise ratio.
In other words, while in theory lidar detectors work, in practice they just aren't functional.
By the way, I'm by no means an expert in the field, my experience comes from some of the engineering companies I've done business with in the past.
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