Why aren't airliners spin-tested? According to Wikipedia, only single-engine aircraft with an MTOW no greater than 12500 pounds are required to demonstrate the ability to recover from a spin, and not large or multi-engine aircraft.  This seems backwards to me, as it would seem to be far more critical for an airliner with potentially hundreds of people on board to be able to successfully escape from a spin than it would be for a small GA aircraft where only the pilot's life is at stake, and not anyone else's.

Can someone explain this seeming contradiction?
1. Spins are less frequent on large aircraft

They are less maneuverable
They are flown by more experienced pilots
They have more protection systems (e.g. flight envelope protection, yaw damper) to avoid uncontrolled flight

2. Spins may cause structural damage on large aircraft
The larger the aircraft, the lower its tolerance to stress. While one can quite comfortably spin a Cessna or Cherokee, attempt one on a Boeing 777 and things will break. Gear doors, the bolts holding the vertical stabilizer as well as cabin accessories are not designed to handle stress in that direction, not to mention engine flame-out.
3. Spins may not be recoverable
As discussed in this question.