It's hard to tell, but the odd coloring on the backs of the wheels, and the shininess on some of the treads make me think that these may be used sets on their way to a recycler.
Funny, I was about to post this picture on its own thread, until I found this one Taken this afternoon near West Covina, CA on the San Bernardino (10) Freeway...possibly en route to BNSF's San Bernardino or UP's West Colton shops: