If you recall the old Federal Express colour scheme was mainly purple over the fuselage of the aircraft. When they changed the corporate image to FedEx one of the changes was the colour schemes of the aircraft - they went mainly white with only a purple tail. Apparently purple paint was heavier than white so this resulted in considerable cost savings over the long term I'm told.
Also I suppose, as white will readily reflect heat (or light) less money would be spent on keeping the cabin temp right for the pax.
However white aircraft are usually pretty dirty looking up close - one of the trade offs I guess.
Oh and one last thought - white makes them easier to see if one accidently gets parked in trees or something!!!
6080ft