We don't have a MC D's here but there are a lot of KFC's. I think that it is up to you whether or not the guests clean up after themselves. I do, but I don't think a lot of the locals do. The staff are kind of expected to do that for the customers, which is an odd notion for me coming from USA where that would never happen at a fast food restaurant.
I'm guessing the drain covers were stolen so they could be sold for scrap. Sounds like something that would happen here and now that you mention it, I don't think the drain covers are made of metal here either.