Three separate places I went to at 8 in the morning. Gas station, dunkin' donuts, and then a convenience store. All of them, trash is full. People wonder why they litter in the USA, there's nowhere to throw away trash when you're out. It's unbelievable People can just go to work and choose not to do their job anymore. That people see this and they don't have any problem with it, no interest at all to keep things neat and tidy and clean. Nope.
Eh, It's a bit of both. No amount of societal pressure will solve a complete absence of waste disposal infrastructure. It's a matter of making sure the sense of shame and/or duty is greater than whatever distance there inevitably is to a working bin.
Uh, history? Almost all of it. You think that's the history of a nice species? Or do you think everyone has spontaneously become nicer, just for this generation? We haven't, at least not appreciably; we just have stronger institutions now to manage it.
Also, it's way more than 4%. I'm guessing it's a majority that would agree with that statement. There's even religions about it. Weren't you the one just complaining about everyone being littering savages? Hopefully you don't just mean people not where you live - that would be a very historical thing to think.