This isn’t some new development. Anyone who’s had regular drug testing in the last 20 years is aware of this. Clearly, you haven’t had a regular drug testing requirement for a job, parole, or any other reason.
If you had, you would know that modern tests moved the threshold of detection up because of these issues on early era drug tests, which is why this idea persists.
I won’t call it a myth, because it’s always possible a batch of food grade poppy seeds wasn’t properly processed, and that batch has unusually high alkaline contents, or that someone consumed a disgustingly large amount of poppy seed muffins, or salad dressing, a day before their test, but that would be the exception, not the rule.
Also, have you never had the poppy seed salad from costco? The dressing is in a small plastic ramekin with at most, a tablespoon of poppy seeds, but probably less.
If alcohol consumption fixed declining birth rates, Japan wouldn’t have an aging population and Russia wouldn’t have been facing a demographic collapse even before the Ukraine invasion.
This isn’t about boosting sex, it’s about being a conservative policy counterweight to opening the door to legalizing medicines derived from cannabis.
My guess is that it’s a result of an internal NJP compromise between center right and hard right factions: only agreeing to allow liberalized medical cannabis policy, if the law also increased the scope of, and penalties for, recreational uses.
But that’s just my assumption based on my limited understanding of Japan’s post-war uniparty government.