Well I guess that's the answer we can give them, but i would have thought that someone has been pulled over on suspicion of having something since the cop got a zero read and was curious.
Also cops are not stupid and I would think some if not all of them would know about the AL system.
Legally they may not be able to do anything as you can state as you said they are parking sensors.
Just wondering if anyone had been pulled over and how they went if they we're give a hard time or not