Yes, poppy seeds are the seeds of the poppy plant which is a large component of opium. But they are not actually opium and your body tends to digest the seeds (which are likely already broken down by the cooking process and however long they were in a jar) different than if you were to process and smoke or inject them. Which tends to lead toward trace amounts that should be below most thresholds… unless you are particularly dehydrated or otherwise didn’t digest the seeds properly.
A big part of the issue is that reputable research on how much you can get away with for a piss test tends to not be funded for whatever reason. It is the same reason that it is generally fine to use hemp based products (e.g. Dr Bronner’s) but nobody will ever put that in writing because there are too many unknowns and it just leads to a mess.
Or, going back to smelling something dank at a concert or on a trail? Guidance was always to be terrified and run away to at least five states over. But the reality is that you basically would need to be hot boxed to get enough contact THC from that. But the threshold between “someone in this outdoor venue is smoking a marijuana cigarette” and “I am stuck in a cloud of weed smoke” is very dependent on far too many factors. So it is easier to say “You get paid enough to just avoid it”
And of the less reputable studies (such as the “I am gonna eat poppy seeds and then piss hot”), they tend to have VERY wildly varying seeds. So stuff like fresh seeds off the plant and so forth.
Which is why I still find it wild that they would go from single piss test to action without a blood test. But not THAT wild since blood tests take significantly more time and money.