moved as this is not an actually support topic sort of thing.
The prices were set long ago, they won't (and can't) be changed until the VBU. As to the 'why' probably because the green plates existed long before food dishes did. I'm guessing that when dishes were implemented along with the diet system, someone simply made a new plate graphic for the time and coded that. We've got plenty of plates, cups and utensils and various other items that are purely for aesthetic purposes. Green plate is one of them
p.s. Who here has actually seen a Quill?