Did you guys have a black tag with a code on it, attached to your key(s)? I was in a rush to pick my car up, thought I heard the salesmen say it was my radio code. According to the manual, it should be my key code. Now, I'm not sure, first 2 characters are letters, followed by 4 numbers.
I'm speculating right now but I think there probably was a black tag with code. And if you didn't get one there might be a very good reason for it if the vehicle was financed. If the code is known, it is easy for the repo man to cut a blank key to fit the vehicle in question and just drive the car away.
As I said, I am speculating but I can speak from personal experience in that many centuries ago I worked in a loan office and we had the sales contract with the key code and when we wanted a vehicle picked up, simply give the code to the repo agency; they cut a key and presto, chango, the car car disappears with no hassle.
Next time I'm at the dealer I'm going to inquire about this. I have a vague recollection of this but it might have been for another vehicle. That would be the one valid reason I can think of why the new owner wouldn't also be given the code for safe keeping in the event both keys were lost or stolen. To have a locksmith come and get into a vehicle lacking the code is bound to be uber expensive. With the code, he could simply cut a new key and you'd be off and running.
I stand to be corrected but I thought I would throw this out. If you paid in full, the dealer should have given the black tag to you as they had not valid reason to retain it.