This is almost formalized in UK trains under TUPE. Train companies like Avanti exist as shells; they don't own track, trains, or stations, and when the franchise shifts to a different company the vast majority of the staff are taken on. Because - guess what - they're the people who can do the job and are in the right place.

Someone called this form of privatization accounting "playing at shops". It is slowly coming to an end as they are re-nationalized.