You also need to look at it from the scrappers point of view.

1. Do i make 2 stops now for a few extra bucks.
2. Am i really making a few extra bucks? Some cases weigh 5 times more than others.
3. 90% of the scrappers near me are illegal immigrants / out of work minorities. Even approaching them to say "HI" they jump in the car and run like your pointing a AK47 in their direction.