I suspect the main point here is that, generally, it is accepted that side on moorings are more expensive than stern on. Take Oulton Broad Y S, as an example. Its very clear that there is a different pricing structure depending how you choose to moor. In my own experience it has always been either, or, I cannot recall being charged for the length of my boat on a stern on mooring. I also suspect this might be at a rather popular mooring!