One thing that is sorely lacking in Korea is the use of TRASH CANS!!! If you finish your coffee and you're walking down the street, you will almost never find a public trash can to drop your disposable cup in. What you will find are these big piles of trash that people have added to as the day goes on, then they get cleaned up at night by the ajummas and ajusshis who comb the streets and freshen up the city.
ONCE IN A WHILE you'll actually see a trash bag tied up somewhere that acts as a trash can. Example above. Actual trash bins are even more rare. What I don't understand: trash cans serve a purpose, both economically and environmentally. What developed city wants giant piles of gross all over the place, uncontained? I just don't get it. HEY KOREA, WHY DON'T YOU HAVE MORE TRASH CANS??? Please make it better soon. Everyone in Korea will appreciate it.
Side note about trash: notice how the bag in the picture above has writing on it? You have to purchase specific bags to be picked up on trash day. There isn't a municipal tax for waste pickup at your apartment, so the sale of the bags is how the city funds the trash pickup. Plenty of people don't follow the rules (see my alleyway at any time and you'll have that proof), but generally you're supposed to buy the bags if you want to throw away your garbage. Good in theory, not good when people completely ignore the rules and just throw their junk in the alley next to your apartment, making everyone navigate over a giant pile of gross to get to your place. See a proper example below: trash in the printed bags, recycling ready to be picked up in an unmarked bag. (Ajummas and ajusshis come by periodically and pick up recycling too. They're the backbone of the whole country. Korea would fail without them!)
*ajumma = old woman; ajusshi = old man