Ground work is really popular in Japan because the snowboarding scene is much more closely tied to the street skating scene. Here, vert freestyle across 3 disciplines (BMX, skate, Inline skating) has been the heavy emphasis for years before freestyle snowboarding really kind of took off and went full on mainstream in the late 90's. Street comps where never given the same level of precedence or attention. So when snowboarding did catch on, naturally it went the same way (vert) eventually maturing the slopestyle scene too.
The result street snowboarding and consequently, buttering, isn't nearly as popular. If you ask me, the Japanese area bit too obssessed with ground work. I have a friend who lived in Japan and became obssessed with their culture - a real otaku or whatever they call themselves - and I constantly am forced to watch the newest buttering edit. I'm also stuck buttering the greens half the day, too. Boring.