In a dispute, I planned to act just like any other resolution process would and review evidence.
Buyer claims a bricks were shipped - What is the weight of box of bricks and does that match the courier/shipping records? How does the seller respond when asked to prove bricks were not shipped?
A smart "brick shipper" would of course make the weight of the bricks match the weight of the item they sold. My point is: you can't really only escrow the financial side of a deal, you need to check both ends.