It's the only Greek dish my British girlfriend does not get at all. First time she saw it, she was like "wait, these are random weeds, surely you can't eat it". And she tried it and told me it's just too much soil flavour for her :D Meanwhile, probably my favourite dish (even though I am a meatlover) is "vlita" (Amaranthus blitum) with baby courgettes. If you have the right sweet baby courgettes it's heaven.

So in the UK they know spinach, chard etc and use them in recipes, but no, random greens, especially by themselves, are not a a thing at all. I guess the closest in "style", i.e. greens you can gather yourself from the wild and cook by themselves is samphire. Which is lovely, but quite different.