California has always shocked me with the amount of trash I encounter on the highways. It's completely different from where I grew up in the midwest, not all of America is like that.
It's part of why I stopped riding motorcycles. There was far too often substantial hazardous objects like building materials or furniture littering the streets. I presume it was all falling from improperly loaded vehicles, perhaps people underestimating the effects of hills.
I've observed a lot more negligence and incompetence in general with Californians. There's a combination of extreme carelessness and lack of ownership for one's (in)actions, I'm not sure how to describe it, but it's very apparent after living here for over a decade. Everything is someone else's problem, maybe it's just the ubiquitous self-centeredness Californians are known for.
In any case, it doesn't make for a population that cooperates on keeping the place clean. The state would have to spend far more than other states to clean up after its residents enough to be kept comparably tidy. These people simply can't be bothered about anything other than themselves.