Different context, I think. If solely the context between Road-Runner and the coyote, he cannot speak but can only hold up signs that speak for him... as does the road-runner when needed. I don't think the coyote was ever referred to as "Wil-e-Coyote" in the road-runner context. Just "Coyote" with the taxon names at times. Same for the road-runner. All the rules, totally followed to the letter.
In fact, in the Bugs Bunny Context, I think some of those Road-Runner rules are broken. Rule 2, for one thing. In the "Operation Rabbit" short, plan #5 involves him filling carrots with Nitroglycerin, all inside an explosives shack. But, unbeknownst to him, Bugs has moved the shack via tractor onto a set of active railroad tracks. One knows what happens, thereafter.
I don't think that's a result of the Coyote's "ineptitude," unless you flunk him on his lack of SA.