I don't think the GATSO uses inductive cables, it uses radar. The truvelos use inductive cables in the road.

The GATSO will also be to the rear of you, to catch your rear number plate and also make sure your not dazzled by the flash. The camera and flash unit are combined so if were flashed then there was a camera inside, you still might get away if it ran out of film which, if it's a busy road is a possibility. You can spot an empty GATSO because the flash unit is quite visible in the little hole in casing.

The truvelo is digital, so it never runs out of film ('cos there isn't any) it's also IR so there's no flash. It also faces you so it stands a chance of getting your face in the picture. If you go past one above the limit you'll have no idea wether it's got you or not until the letter arrives in the post.