I don't see why inequality for men/women who don't have periods should be an issue. Women get maternity leave because it's acknowledgement of our anatomy that we carry babies, and you get illness discounted at work in acknowledgement that pregnancy can effect woman.
The problem is that the temptation would just be far too great for countless women who are lucky enough to have no need for it, but can’t resist claiming three bonus days off every month that are there for the taking in return for a quick lie that can’t be verified or disproven. Not just women: men would be exactly the same, given the chance, but they obviously wouldn’t be able to blag it! This would have the result of poisoning the well for the women who DO suffer and genuinely need the time off, and we’d just end up with something even nastier than the Bradford Scale, with women automatically falling under suspicion of lying where men simply won’t.
The Bradord Scale is a vile piece of work, and it discriminates against lots of different medical problems, issues and conditions which aren’t kind enough to happen in one big single block to normally-problem-free people and then never return. The BS (appropriate abbreviation) is supposedly designed to eliminate liars throwing sickies, but it actually has the exact opposite effect, meaning that those who are fortunate not to actually get sick can game it to score some good free blocks of holiday whereas those with regular migraines, severe period pain, asthma attacks, neurological flare-ups etc. etc. simply don’t have that luxury and end up being forced to go in to work when they really shouldn’t have to – maybe having to cover extra work for their lucky well colleagues who fancied a nice break courtesy of the BS formula.
Most of these countries you have mentioned which already have menstrual leave are not normally those most closely associated with women's rights.
Yes, I wonder what the whole picture is. Do the women have equal employment rights in the first place, or is the menstrual leave just a patronising sop handed out to the lowly, insignificant, unimportant female workers, in contrast to the male workers who get all of the Big Important Jobs That Actually Matter – as if they were tiny children needing to be allowed regular nap times or something 