I didn't get into specifics before, but even concrete examples as a backup have failed. They'll listen and understand the example on a narrative level ("this is a weed to Person 1 and here's why, but not to Person 2 and here's why,"), but every fibre of their soul is clearly trying to ask indirectly: "okay, but how are weeds defined then?" It's like you'd think they're trying to square a scientific disagreement between Persons 1 and 2; it's like they're trying to figure out who was right.

What's especially crazy to me too is that this has never, I think, been in the context of me challenging what they consider weeds and suggesting they reconsider; it's just come up sometimes. I'm handing them the absolute, irrevocable right to keep their categorization of weeds exactly the same, but they act like a cartoon character trying desperately not to remember they're walking on air.

My dad once told me about a local man when he was a kid who made dandelion wine (I'll have to ask him next time, but I think part of the story is that he was older and paid local kids to gather the dandelions for him).

Still looked like his brain was falling down the stairs when I told him what weeds are. The utility doesn't matter; it's a weed because it proliferates easily on barren, manicured turf, and while you're welcome to feel however you want about the weeds, they're weeds all the same. Not even a spoken argument by him; you could just tell from the follow-up discussion that this is what was going on up there.

Well, many non-natives are not invasive and some natives are invasive. Right plant, right place.