At some point I thought that it absurd on purpose but I had some people explaining me the rationale behind it (there is no rationale - if there is an exception it at best weakens the "rule")
https://en.wiktionary.org/wiki/exception_that_proves_the_rul...
Just as you say, the point is that a rule is implied by a specific exception, as in the example "free entry on Sundays", which implies the unstated rule "pay for entry on other days".
The exception weakens the rule, it's true, but may also reveal the rule.
(if there were no rule, there wouldn’t be any exceptions to it, or nothing would seem exceptional with respect to the (previously unstated) rule)
Eh, what? This wasn't my experience at all. I didn't conduct a study, but I was in a good few bars over there, in three different cities. Can you elaborate on what you're referring to here?
Hooters is a pretty unique restaurant experience in the US and is therefore considered different/further from the norm and frankly by many seedy. If there were more places like Hooters in the US then this would probably not be true.
The comment was trying to explain that in Japan you have a lot of places that would be analogous to Hooters in the US...so it's not exceptional/not seedy. Maybe not quite the "norm" but common enough to not be really something that gets noticed or have a connotation like "seedy".
Unlike the US, Japan has a highly visible and de facto legal sex industry, so if anything sexy izakayas are/were at the less seedy end of the scale.
You're doing entertainment first. A game here, a crazy story there. Nothing to challenging, people want to have a polite, entertaining experience. If they learn something along the way that's fine but they won't really care if they don't.
There was a wide range of students. Some serious, usually planning to study overseas in the future. Some people just there for a hobby or an outlet. There were a few people who came to offload their problems to someone who they felt was outside the normal social structure (and therefore not going to judge them). I think people in general felt they were much freer to speak using English rather than Japanese.
That's true to my experience with Japanese ESL students (not in Japan). Some explicitly told me that themselves; many others had that vibe.