I grew up in the 60s in California, and a huge, *huge* ad campaign was underway during that era. The whole "Keep America Beautiful". There was a memorable commercial featuring an old Native American man, with a wrinkled, wise face gazing at the beautiful stretches of this country strewn with garbage. The last shot shows his face, still stern and calm, but with a tear running down it. What happened to that? Maybe that would be too corny these days.
As I go through Center City, I constantly see people throw trash around cars in front of me, dropping everything from cigarette butts to a whole fast-food bag full of trash onto the street and then driving away. (I honk at them.)
It seems to me that Once Upon A Time, we assumed that only ignorant, rude, degenerate or disadvantaged people dropped litter. I have a perception from somewhere that nice people kept their environments pleasant. They kept their voices and faces neutral, and didn't leave a mess around them, at least in public places. They respected a difference between private and public space.
Maybe that was never true. Certainly these days I can testify that people from every walk of life walk away from their own garbage. And then they complain about the trashy sidewalks.
(I'm married to someone who usually picks it up, rather than walk past it, even though it isn't his).