I had a large load delivered on a pallet. The guy had a motorized dolly (sort of a hand pulled forklift) in the back of his truck and a motorized lift as a tail gate, so he picked up the pallet with the dolly, rolled it onto the lift, lowered it to the ground and rolled it into my driveway. I happened to be home and I unloaded the items by hand into my garage. However if I hadn't been there, it would have been pretty difficult for thieves to steal - they either would have needed to hoist the whole load back into their own truck or unload the box by hand, which would have been tedious and highly visible. Had he left the stuff on a trailer, it might have been easier for thieves to steal both the goods AND the trailer.

Bonus - he told me to keep the pallet.