[alexmat]

You don't need "social awareness" to explain any of your observations:

1) Low income inequality / strong welfare system 2) This is actually a counter example. Nothing more socially offensive than second hand smoke. 3) Trash cans disappeared from the streets of Tokyo shortly after the sarin gas subway attack by Aum Shinrikyo in 1995, and they've never reappeared.

[adrianN]

But even without trash cans, Japanese people don't litter, ever. In contrast, Berlin, where I currently live, has lots of trash cans but the streets are full of litter.

[paublyrne]

Berlin doesn't get cleaned enough by the city. Yesterday it was still covered in fireworks and empty wine bottles from New Year's Eve. The only reason it looks clean today is because it's covered in snow.

If it were cleaned more regularly people wouldn't litter so much. (Not a defence of people who litter, and it's the one thing I hate most about living here.)