[addaon]

I don't know if there are people who treat turquoise and aqua as distinct, but I certainly treat them as distinct from blue (azure, cobalt) and green. Several of the colors around the mid range in the linked page are not colors I would use the words "blue" or "green" for. That doesn't mean that I have strict rules here; I don't actually know if I would call what you call "cyan" turquoise or blue; ditto plenty of other words like "seafoam." That's kind of my point -- modulo another poster's comment about this being a test of bad monitor calibration, it's really more about language than about color.

I think there's another set of questions here -- why is "blue-green family" a thing in your mind, rather than "blue-yellow family"? Is there a "red-blue family"? "Orange-blue"?

[seba_dos1]

Our green cones are the most sensitive and their range significantly overlaps with red cones, so it's only natural that going from green towards red you'll be able to make clearer distinctions between colors than the other way.

Also, yellow-blue and red-green are opponents that can't be mixed because of how our retinas preprocess the signals from cones. Therefore, you obviously end up with blue-green (cyan), red-yellow (orange), yellow-green (lime) and blue-red (magenta, which actually doesn't exist on the light spectrum) families of related colors.