Who performs repossessions of airplanes?
Yes there are a couple of reality TV shows that have been done on repos.  There are companies who specialize in the business, and the pilots have to be type rated where appropriate.  They have to be legal to fly the airplane.
It takes a special kind of risk taker pilot to do that kind of work, in view of the risks of getting into confrontations with irate owners, and flying airplanes that may or may not be airworthy.  The companies are usually hired by the holder of the chattel mortgage on the aircraft; the lender in other words (and who is, ultimately, the owner).  Banks and leasing companies generally, and even government foreign aid financing organizations from time to time.
Yes the scenarios presented on the tv shows are semi-fictional BS,  with dopey staged chase scenes, but even dialing the drama back closer to reality, it's not a job for the faint of heart.