The ground handlers that handle your luggage work for the airline, at least that's the way it's done in the US.
I have heard of airports in Europe that do their own luggage handling, but I would assume that it is done through a contractor.
Tom in NO (at MSY)
PS: Please, please don't blame airports for lost luggage!!! Honestly, it's not our fault.
"The criminal ineptitude makes you furious"-Bruce Springsteen, after seeing firsthand the damage from Hurricane Katrina