The difference between decency and trashing the joint
It is no coincidence that the third kind is a child. The girl in this story could well have received guidance in kindergarten on what is the right thing to do, but her grandmother, with her worldly experience, is conditioned to look after her own interests - even at the expense of public interests. When she was at school, China could be mired so deeply in poverty that public amenities did not include garbage bins.
Unlike small towns in Western countries, Chinese towns did not have public services like garbage collection until very recently. And some still do not have it. That explains the ubiquitous squalor and the habit of littering in public spaces. When you have clean streets you may hesitate before tossing unwanted stuff into them.
So civic consciousness is not just the responsibility of the individual. First of all, the basic public service of garbage collection has to extend all the way to small towns and rural villages. You cannot expect someone used to big piles of trash outside his door to suddenly change his behavior as soon as he sets foot in a squeaky clean metropolis. Then there is education, which should drum home the point that it is a matter of human decency to respect the environment shared by all of us.
Right now we are living in an age of fast changes when the economy of much of the country is respectably middle class yet the mentality and civic codes lag behind. We'll catch up, but a constant reminder is necessary of the distance we have to go.