Being in a first-world society confers one with a mind-set completely different from those of second or third-world societies. Just over a century ago, first-world countries were not much better from the third-world countries of today, and it will come as no surprise that littering and spitting and even open urination and or defecation were common in those days.
Today, there is hardly any open urination or defecation in the first-world and littering has been reduced to a minimum. In the near future, as the third-world is battling with how to catch-up with the first in terms of sanitation, the latter will not falter in making sure the gap continues to be a bit wide, at least in the sanitation aspect.
Nowadays littering is one of the global issues for the humanity. Due to scientist from the many other countries prognosis that if this process had been continued half surface of the earth would have been covered by litter. The litter is a artificial product which using thrown away as useless and could not decay itself.
I'm one of those people who will carry my litter in my purse until I get to a garbage can, so it annoys me thoroughly when I see someone just toss something on the ground. First world societies take so much for granted. There is a sense of entitlement where we feel that someone else will clean up after us. It's obnoxious.
I doubt littering will ever be eradicated. People can be forgetful, absent minded, or in the moment and things can get left behind. I hope it becomes less of an issue especially with regards to our oceans and parks. But things happen, sometimes you just miss the trash or things get taken by the wind and you can't stop it. I don't think I've ever seen anyone purposefully litter so I'm not sure if that's part of the issue or not.