Trashing the Plane

Even on flights of three hours or less, upon departure it's hard not to notice how badly passengers have trashed the plane.
As you proceed down that long, narrow aisle, you can see quite clearly that people have left food wrappers, crumbs, empty cups and cans, magazines, newspapers, and personal belongings.
Sure, flight attendants are supposed to pick things up before the plane lands, and
ground crews come in and clean the cabin after the plane lands. Still, is that any reason for 100 to 300 passengers to leave the place a total mess?
What does it say about our ability to control our environment when we can't keep a plane interior clean for a couple hours' ride? What have we become?