Probably the biggest reason Shonen Knife is fairly well-known over here is because many bands in the U.S. indie rock and grunge scenes during the late '80s/early '90s were big Shonen Knife fans. Most notably, Kurt Cobain of Nirvana and Thurston Moore of Sonic Youth were/are big fans, and that got Shonen Knife a lot of publicity (along with a major record label deal) when they were breaking in America. Shonen Knife opened for Nirvana several times, and Thurston Moore played on one of their records (along with participating in SK's first remix record). Also, Shonen Knife continues to release records and tour America to this day - and unlike Puffy and other Japanese bands who have played the U.S., SK does full, cross-country tours, instead of playing a few dates in L.A. and New York exclusively (or just sticking to the coasts).
In short, what Naoko said in the interview with melody. Also, I think the fact they release all their records over here in English is a big help - a lot of people dismiss Japanese music immediately because of the language barrier, so having a songwriter fairly fluent in English helps a lot.
Having said that, Shonen Knife isn't super popular over here at all; they released two records while signed to a major label, and since have released their records on smaller or independent labels. I'd say their popularity is on a similar level to Puffy - they have a somewhat small, but very dedicated, group of fans. When I saw them live last November there were maybe 100 people in the club, which is probably a slightly smaller crowd than the one at the Puffy concert I saw back in 2006.
