Hunter:
Your airline market observations are logical and easily understood. But the real world of aerial freight markets is a dog eat dog phenomena wich defies ordinary logic.
Shipping rates and earliest airplane availability drive the market. There is no brand loyalty. The shipper of perishables wants his time sensitive cargo delivered TODAY at the LOWEST cost. He doesn't care what color the airplane is or whether the airline also carries a competitor's freight.
The asparagus on the tarmac at Lima will not necessarily wait for one belated Polar or Atlas 747 flight to come through. It may go on the Lan Chile 767F that's on the ramp right now with available space, with a shipping rate negotiated on the spot. Perishable cargo is a slippery business. Worldwide.