Why is it that Japan, Germany, and Sweden all took rock music to an art form and anglo countries did barely anything interesting with it (with a few exceptions)?
Germany and Japan are technologically forward and culturally bent on seeking excellence, combined together giving them the incentive to look for new technologies and exploit them for their full potential. Sweden has an extensive public music education system that causes it to consistently produce great musicians. These are also all developped countries which fosters development of the arts, although that is also true of the UK and US. I'd disagree anglo countries did barely anything interesting with rock music, although there is an explanation why so many pioneering bands originate from the 3 countries you've named.
I'm not saying they made ART MUSIC. It's obviously all popular music I posted. My point was that after America and England started making rock music, Japan and all the other countries I mentioned created rock music fucking lightyears better.