In Daves case the way in which the roaster works is the problem. It is designed so that the beer or whatever liquid you are using to keep the bird moist is outside of the cavity.
I think you're misunderstanding here, Rich. The Weber unit has a cup for the liquid that goes inside the bird as with any of these devices. The big pan is only designed to catch the juices and prevent them from running into your grill. Drilling holes would prevent the runoff from collecting in the pan, but I don't think it's necessary.