Of course ... "we won't bother'" would never fly (pun alert again) and not one I suggested, but as you know ... the caveat of 'reasonably practicable' would be considered and I would stake everything I own that as long as a club could prove that they have a pre-match cleaning regime in place, then a succesful prosecution on preventing a bird naturally depositing mess in an open stadium at any given time would be zero ... however, if there was no cleaning done then ... best of luck defending that position I agree!