China Encourages Littering

So I saw this sign above a window on a train, and I was pretty confused as to what it was trying to tell me. Back in the states, seeing a circle with a line through it means you cannot do whatever is in that circle. If you see a sign with no line through it, that generally means you are allowed, if not encouraged, to do it! So when I see a sign with a man sticking his head out the window, and a bottle being tossed out that same window, what am I supposed to think? Come on China!