When I was a college student, several of us were authorized to drive the campus van. We had to have a reference check and submit our licenses in order to be “on the list.”

We didn’t have to maintain the vans or fuel them, but were ocassionally authorized to take them out for school business. The authorizing department had to reserve the vehicle, but we had to go check out the key in order to drive them. And... we had to bring back the key when we were done. You can imagine the chaos if someone forgot to return the key.

Is this relevant? I don’t know. We only had 5 or 6 vans, that returned to the same campus each night. Even so, we had to have a system (and personnel) to control the keys. I can’t imagine key control for a fleet of aircraft that move around the country. It would likely require a single full-time employee at each airport and an extra 5-10 minutes of time on every pilot’s time sheet. Failure to return a key at the end of a shift could result in an entire plane of pax cooling their jets.