As mentioned in this thread, the car manufacturers don't seem to be overly bothered about making their cars secure enough to determine thieves.
The trouble with car security/ technology is that the professional criminals have access to the equipment to overcome all their attempts to Foil them.
As for storing the keys information on the ECU
As not relevant in the OP case, but even more ridiculous is keyless entry
Makes the crook locks from the 1990's look advanced.