I like plenty of live music yeah (folk, idol pop, metal, ...). That kind of "jazz cafe" doesn't usually do live music though, so I'm a bit confused by the question.
Where I’m from, that implies nightly live jazz performances from relatively to extremely talented musicians. I have never been to Japan, so I was unaware that I probably am missing context.
While you're right that it's usually jazz kissas, the Sasebo bar[1] I mentioned had instruments for live playing - sort of like a mini-studio. Apparently some patrons might play rock there sometimes. But yes, I assume it was mostly about listening to recorded music.
The owner said that young people were leaving Sasebo for bigger cities with more work, so that was draining the vitality of the area. A common story all over Japan, as you probably know.
I've also been to jazz clubs in Japan and those are cool, but clearly a dying breed given the ages of the audience and most of the musicians. At a matinee at the historic Shinjuku Pit Inn, I think I was among the youngest members of the audience. Similar story at smaller, more intimate spots. It's just a declining trend with long-time regulars and not much new blood.
It’s interesting how many people wrongly assumed that a Japanese jazz bar (jazz kissa) with recorded music was the same as a Western smoky jazz bar with live music.
Assumption is such a weirdly human anti-pattern.
1. It’s surprising we as humans don’t walk right into a Lemmings like disaster and massacre ourselves.
2. I highly doubt that HN is more or less enlightened but I do wonder if HN is more or less likely to have dissenting, informative, fact checking voices compared to let’s say a boar hunting forum