> Eyes can't be blue either.

I get what you mean, but this is also like saying a butterfly doesn't have color.

The blue in blue eyes (and green) is a structural property, not a pigment property. This is also why eye color changes for these people much more dramatically than people with darker colored eyes (see Hazel eyes).

It's color caused by structure, but that doesn't make it not a color. A lot of things aren't going to "have color" if you use that definition. Including the sky...

Human eyes aren't pigmented blue, but they are still blue.

Only in the sense that venous blood "is" blue.

We don't see the blood in veins, and it wouldn't be blue if we could, but I would agree that veins are blue.

Human blood can turn blue when consuming enough (collodial) silver?

Like when rich people consumed food and beverages from pure silver plates (100's of years ago) their blood supposedly turned purple/blueish. Hence the term (at least in Dutch) that "he is of blue blood" = he rich af.

Or that's all a myth. Not sure.

> Hence the term (at least in Dutch) that "he is of blue blood" = he rich af.

This is usually said to refer to the fact that someone's skin is so pale you can see the veins through it.

(Also, it refers to pedigree rather than wealth, in English...)

I would expect silver to turn things black, not blue.

(Although see https://en.wikipedia.org/wiki/Argyria )

They would hide from the sun to get extra veiny, because they could

Perhaps, but according to etymonline the term comes from Spain, where certain families described themselves as having "blue blood" to emphasize that they had no Moorish ancestry. The contrast being drawn isn't one between nobles and laborers. It's between indigenous nobles and intrusive nobles.

Like the programmers in our time

see also blue people - https://www.thecollector.com/blue-fugates-kentucky/

elevated methemoglobin in human blood causes brown blood causes blue skin

> there is no blue food

Have you eveer seen a blueberry? Or a Concord grape? Or a damson plum?

Why not?