I don't understand this. I have an older BMW which developed starting problems with the immobiliser computer. It doesn't have keyless entry but it is based on rfid.
I did extensive research on the system and there were three parts - the key, the immobiliser and the engine management computer. The key physically turned the ignition, but the security was in a rfid chip inside the key, which was physically matched to the immobiliser via an antenna ring that circles the lock. The immobiliser was physically matched to the computer via a VIN-based code. If you lost the key, you had to order a new one from germany after producing the VIN and proof of ownership to a licensed dealer. They keys cost about $500 from memory - don't lose the key. There is an upper limit of 10 keys to be produced per vehicle, with two of those supplied upon purchase.
In order to replace the immobiliser computer, again both the VIN and proof of ownership had to be supplied to the licensed dealer, who then ordered a new one from the factory in Germany. You cannot swap any of the parts between cars - you can't reprogram keys, reprogram the immobiliser or reprogram the computer.
If you do put a new computer or immobiliser in, it had to be taken into a BMW dealership to re-sync and get all the devices to handshake each other and agree that they were all legitimate. Otherwise - no start.
I know all this because I tried to hotwire the car myself to get it working until the new computer arrived (3 week order period). While I could manually activate the fuel supply and manually activate the starter, the computer refused to tell the spark plugs to ignite and refused to tell the injectors to inject.
What I'm curious about is how have they gone backwards from this seemingly impregnable system to one where you can get the car to reprogram a key? Surely it can't all be the fault of the OBD port - I doubt there is anything in the legislation calling for the ability to reprogram keys via the vehicle itself? Or is it just the fact that someone has come up with software that replicates what the factory does?
Somehow it all seems a retrograde step. Given that the older systems worked with rfid, whether or not you put the key in seems a moot point.