Why is this so true?

This is true pretty much everywhere. When you visit a place you tend to get a "Disneylandfied" version of it, while you are in "vacation mode", and even the negative parts that sip through come out as quirky in the short amount of time you experience them. When you live in a place you get hammered with the good and bad every single day, all while trying to go though your daily life.

Bonus points if this is in Japan.