one reason ian is they are easy to find and disable on a bike. not too many hiding places. we have these trackers on our wagons and plant, like compressors and generators, but they are nowhere near as dear as these carbugs. these things need a constant voltage to run as far as i know, so if a bike was slung in the back of a van and the battery disconnected, the tracker would be kaput. if they could miniturise them [as they can with most things], fit it with a long life battery, like a bios battery, and tuck it away inside the frame or something, then it would be very useful.
ade!