Because it wouldn't be as fun that way! Package basketball!One time I was dropping off a mailing at the local BMEU and saw firsthand how the USPS handles boxes. The guy had a cart positioned about 15 feet away from him and was chucking various packages from the back of his truck to the bin...
I had so many questions most of them were just .... why? But mostly, the cart is on wheels, why wouldn't you wheel the cart closer? So much effort for so little reason.