Aye, having some sort of chip built into the frame could be good but then the frame gets dumped and the parts sold on…a tricky one that wont be solved soon. As a courier in london, there are a few guys i'm not sure of at all, just don't smell right(probably the case in more ways than one!), but then again is that just my suspicious nature?…i'm as yet unconvinced that some of them don't have a hand in nicked kit…tricky indeed and as the OP says, it's probably the case somewhere for sure.