Are the pavements really that clean or is that photo with the stairs just unrealistic?
I guess it's possible, although that would require near constant vacuuming.
That said, what might contribute to the cleanliness in the photo though is that it was possibly taken after the last train (all trains stop after around midnight), so it's not unlikely the stairs are exceptionally clean because they had just been cleaned before.
On a slightly unrelated note regarding having to be vacuumed constantly, the stairs being clean and the extremely low rate of unemployment in japan might not be unrelated, and on topic it might also not be unrelated to the prevalence of sleeping in situations that would be utterly unacceptable in other countries, such as meetings :)
I used to think Toronto was a clean city. After visiting Tokyo, I see that very few areas in Toronto are actually clean.
However
There's one class of people who believe that it's their God given right to litter wherever and whenever they want, and that's smokers.
You can especially see it around Tram stops where people are waiting around and will quite happily throw their cigarette butts on the ground or pavement when the tram approaches.
Usually between 5 and 6am, that helps keep them clean, too.
(I’m a German who usually wakes up from the sound in the morning)