A big reason was that in the 70s, the recording equipment in Japan was superior to what was commonly seen in the USA or some parts of Europe. The Japanese would bring top-of-the-line gear, and were meticulous about getting good sounds to tape in a live setting. Whereas in the US, a live album was often an afterthought, with whatever gear they could get to a gig as cheaply as possible to record it. There are some 70s and 80s live albums from Japan that still sound better than stuff made since then elsewhere.A few reasons: The Budokan sounds great. 2. Crowds remain quiet during the song, but give huge applause after every song. Drugs are hard to get, so musicians play better?