Escrow service may check if there is a lens or a camera in the box, not a brick.
They may even check if the lens make and model are as ordered, and if physical appearance matches the description.
Will they try to mount the lens on the matching camera to see if it works? Will they inspect aperture for oil? Lens elements for dust and fungus?
Will ANYTHING they do prevent the seller from saying "corners are not as sharp as I expected" and still return the lens?
Or, with a camera, saying "the image quality is not up to my expectations", or claiming an intermittent (once a week) problem?