Used to be a bit of that in Alaska. An aircraft owner would lease himself and the plane to an air taxi and operate on their certificate. Generally paid by the block hour. I remember a lot of individuals that owned an airplane and leased it to an air taxi. Super Cub's, C185's, C206/207, Beaver's, Beech 18's, etc. I talked to Cessna about buying a Caravan when they first came out. If I were more of an entrepeneur I'm sure I could have done well with it. This has been a while, don't know if it still goes on today.

Airborne Express had a couple of feeders that appeared to be 1 or 2 plane operators. I don't know if DHL renewed those contracts or not. I'm thinking of the Beech 18's in CID and MSP. Someone else on the forum should know more about that than I do.